Bug 1102240 - split inspector actor in smaller files;r=ochameau,pbro
authorJulian Descottes <jdescottes@mozilla.com>
Fri, 26 Jan 2018 13:11:58 +0100
changeset 401505 8e3c63c83301f63943e08a4a4284ee28bb1b1ee9
parent 401504 4c42b9b8bd98c6f378f94a6fc896d4a58964ec67
child 401506 17a0e7ddfb483356fb7caaee66fb2170b7d45dfe
push id33346
push useraiakab@mozilla.com
push dateTue, 30 Jan 2018 21:59:39 +0000
treeherdermozilla-central@5fc179e245d5 [default view] [failures only]
perfherder[talos] [build metrics] [platform microbench] (compared to previous push)
reviewersochameau, pbro
bugs1102240
milestone60.0a1
first release with
nightly linux32
nightly linux64
nightly mac
nightly win32
nightly win64
last release without
nightly linux32
nightly linux64
nightly mac
nightly win32
nightly win64
Bug 1102240 - split inspector actor in smaller files;r=ochameau,pbro MozReview-Commit-ID: LgZav4dMQRR
devtools/client/inspector/markup/test/actor_events_form.js
devtools/client/inspector/markup/test/browser_markup_textcontent_edit_01.js
devtools/server/actors/highlighters/box-model.js
devtools/server/actors/inspector/document-walker.js
devtools/server/actors/inspector/inspector.js
devtools/server/actors/inspector/moz.build
devtools/server/actors/inspector/node-actor.js
devtools/server/actors/inspector/utils.js
devtools/server/actors/inspector/walker-actor.js
devtools/server/actors/moz.build
devtools/server/actors/webextension-inspected-window.js
devtools/server/tests/mochitest/inspector-helpers.js
devtools/server/tests/mochitest/test_inspector-anonymous.html
devtools/server/tests/mochitest/test_inspector-insert.html
devtools/server/tests/mochitest/test_inspector-mutations-value.html
devtools/server/tests/mochitest/test_inspector-traversal.html
devtools/server/tests/unit/test_nodelistactor.js
--- a/devtools/client/inspector/markup/test/actor_events_form.js
+++ b/devtools/client/inspector/markup/test/actor_events_form.js
@@ -6,17 +6,17 @@
 // This test actor is used for testing the addition of custom form data
 // on NodeActor. Custom form property is set when 'form' event is sent
 // by NodeActor actor (see 'onNodeActorForm' method).
 
 const EventEmitter = require("devtools/shared/event-emitter");
 const {ActorClassWithSpec, Actor, FrontClassWithSpec, Front, generateActorSpec} =
   require("devtools/shared/protocol");
 
-const {NodeActor} = require("devtools/server/actors/inspector/inspector");
+const {NodeActor} = require("devtools/server/actors/inspector/node-actor");
 
 var eventsSpec = generateActorSpec({
   typeName: "eventsFormActor",
 
   methods: {
     attach: {
       request: {},
       response: {}
--- a/devtools/client/inspector/markup/test/browser_markup_textcontent_edit_01.js
+++ b/devtools/client/inspector/markup/test/browser_markup_textcontent_edit_01.js
@@ -2,17 +2,17 @@
 /* Any copyright is dedicated to the Public Domain.
  http://creativecommons.org/publicdomain/zero/1.0/ */
 
 "use strict";
 
 // Test editing a node's text content
 
 const TEST_URL = URL_ROOT + "doc_markup_edit.html";
-const {DEFAULT_VALUE_SUMMARY_LENGTH} = require("devtools/server/actors/inspector/inspector");
+const {DEFAULT_VALUE_SUMMARY_LENGTH} = require("devtools/server/actors/inspector/walker-actor");
 
 add_task(function* () {
   let {inspector, testActor} = yield openInspectorForURL(TEST_URL);
 
   info("Expanding all nodes");
   yield inspector.markup.expandAll();
   yield waitForMultipleChildrenUpdates(inspector);
 
--- a/devtools/server/actors/highlighters/box-model.js
+++ b/devtools/server/actors/highlighters/box-model.js
@@ -13,17 +13,17 @@ const {
   hasPseudoClassLock,
   isNodeValid,
   moveInfobar,
 } = require("./utils/markup");
 const {
   setIgnoreLayoutChanges,
   getCurrentZoom,
  } = require("devtools/shared/layout/utils");
-const inspector = require("devtools/server/actors/inspector/inspector");
+const { getNodeDisplayName } = require("devtools/server/actors/inspector/utils");
 const nodeConstants = require("devtools/shared/dom-node-constants");
 
 // Note that the order of items in this array is important because it is used
 // for drawing the BoxModelHighlighter's path elements correctly.
 const BOX_MODEL_REGIONS = ["margin", "border", "padding", "content"];
 const BOX_MODEL_SIDES = ["top", "right", "bottom", "left"];
 // Width of boxmodelhighlighter guides
 const GUIDE_STROKE_WIDTH = 1;
@@ -671,17 +671,17 @@ class BoxModelHighlighter extends AutoRe
     if (!this.currentNode) {
       return;
     }
 
     let {bindingElement: node, pseudo} =
         getBindingElementAndPseudo(this.currentNode);
 
     // Update the tag, id, classes, pseudo-classes and dimensions
-    let displayName = inspector.getNodeDisplayName(node);
+    let displayName = getNodeDisplayName(node);
 
     let id = node.id ? "#" + node.id : "";
 
     let classList = (node.classList || []).length
                     ? "." + [...node.classList].join(".")
                     : "";
 
     let pseudos = this._getPseudoClasses(node).join("");
copy from devtools/server/actors/inspector/inspector.js
copy to devtools/server/actors/inspector/document-walker.js
--- a/devtools/server/actors/inspector/inspector.js
+++ b/devtools/server/actors/inspector/document-walker.js
@@ -1,3055 +1,24 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
-/**
- * Here's the server side of the remote inspector.
- *
- * The WalkerActor is the client's view of the debuggee's DOM.  It's gives
- * the client a tree of NodeActor objects.
- *
- * The walker presents the DOM tree mostly unmodified from the source DOM
- * tree, but with a few key differences:
- *
- *  - Empty text nodes are ignored.  This is pretty typical of developer
- *    tools, but maybe we should reconsider that on the server side.
- *  - iframes with documents loaded have the loaded document as the child,
- *    the walker provides one big tree for the whole document tree.
- *
- * There are a few ways to get references to NodeActors:
- *
- *   - When you first get a WalkerActor reference, it comes with a free
- *     reference to the root document's node.
- *   - Given a node, you can ask for children, siblings, and parents.
- *   - You can issue querySelector and querySelectorAll requests to find
- *     other elements.
- *   - Requests that return arbitrary nodes from the tree (like querySelector
- *     and querySelectorAll) will also return any nodes the client hasn't
- *     seen in order to have a complete set of parents.
- *
- * Once you have a NodeFront, you should be able to answer a few questions
- * without further round trips, like the node's name, namespace/tagName,
- * attributes, etc.  Other questions (like a text node's full nodeValue)
- * might require another round trip.
- *
- * The protocol guarantees that the client will always know the parent of
- * any node that is returned by the server.  This means that some requests
- * (like querySelector) will include the extra nodes needed to satisfy this
- * requirement.  The client keeps track of this parent relationship, so the
- * node fronts form a tree that is a subset of the actual DOM tree.
- *
- *
- * We maintain this guarantee to support the ability to release subtrees on
- * the client - when a node is disconnected from the DOM tree we want to be
- * able to free the client objects for all the children nodes.
- *
- * So to be able to answer "all the children of a given node that we have
- * seen on the client side", we guarantee that every time we've seen a node,
- * we connect it up through its parents.
- */
-
 const {Cc, Ci, Cu} = require("chrome");
-const Services = require("Services");
-const protocol = require("devtools/shared/protocol");
-const {LongStringActor} = require("devtools/server/actors/string");
-const promise = require("promise");
-const defer = require("devtools/shared/defer");
-const {Task} = require("devtools/shared/task");
-const EventEmitter = require("devtools/shared/event-emitter");
-const InspectorUtils = require("InspectorUtils");
 
-const {walkerSpec, inspectorSpec} = require("devtools/shared/specs/inspector");
-const {nodeSpec, nodeListSpec} = require("devtools/shared/specs/node");
-
-loader.lazyRequireGetter(this, "DevToolsUtils", "devtools/shared/DevToolsUtils");
-loader.lazyRequireGetter(this, "AsyncUtils", "devtools/shared/async-utils");
-loader.lazyRequireGetter(this, "CssLogic", "devtools/server/css-logic", true);
-loader.lazyRequireGetter(this, "findCssSelector", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "getCssPath", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "getXPath", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "colorUtils", "devtools/shared/css/color", true);
-loader.lazyRequireGetter(this, "EyeDropper", "devtools/server/actors/highlighters/eye-dropper", true);
-loader.lazyRequireGetter(this, "WalkerSearch", "devtools/server/actors/utils/walker-search", true);
-loader.lazyRequireGetter(this, "PageStyleActor", "devtools/server/actors/styles", true);
-loader.lazyRequireGetter(this, "getFontPreviewData", "devtools/server/actors/styles", true);
-loader.lazyRequireGetter(this, "flags", "devtools/shared/flags");
-loader.lazyRequireGetter(this, "throttle", "devtools/shared/throttle", true);
-loader.lazyRequireGetter(this, "LayoutActor", "devtools/server/actors/layout", true);
-loader.lazyRequireGetter(this, "HighlighterActor", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "CustomHighlighterActor", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "isTypeRegistered", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "HighlighterEnvironment", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "EventParsers", "devtools/server/event-parsers", true);
-loader.lazyRequireGetter(this, "isAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "isNativeAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "isXBLAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "isShadowAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "getFrameElement", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "loadSheet", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "getLayoutChangesObserver", "devtools/server/actors/reflow", true);
-loader.lazyRequireGetter(this, "releaseLayoutChangesObserver", "devtools/server/actors/reflow", true);
 loader.lazyRequireGetter(this, "nodeFilterConstants", "devtools/shared/dom-node-filter-constants");
-
-loader.lazyServiceGetter(this, "DOMParser",
-  "@mozilla.org/xmlextras/domparser;1", "nsIDOMParser");
-
-loader.lazyServiceGetter(this, "eventListenerService",
-  "@mozilla.org/eventlistenerservice;1", "nsIEventListenerService");
-
-const FONT_FAMILY_PREVIEW_TEXT = "The quick brown fox jumps over the lazy dog";
-const FONT_FAMILY_PREVIEW_TEXT_SIZE = 20;
-const PSEUDO_CLASSES = [":hover", ":active", ":focus"];
-const HIDDEN_CLASS = "__fx-devtools-hide-shortcut__";
-const SVG_NS = "http://www.w3.org/2000/svg";
-const XHTML_NS = "http://www.w3.org/1999/xhtml";
-const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
-const IMAGE_FETCHING_TIMEOUT = 500;
-
-// Minimum delay between two "new-mutations" events.
-const MUTATIONS_THROTTLING_DELAY = 100;
-// List of mutation types that should -not- be throttled.
-const IMMEDIATE_MUTATIONS = [
-  "documentUnload",
-  "frameLoad",
-  "newRoot",
-  "pseudoClassLock",
-];
+loader.lazyRequireGetter(this, "standardTreeWalkerFilter", "devtools/server/actors/inspector/utils", true);
 
 // SKIP_TO_* arguments are used with the DocumentWalker, driving the strategy to use if
 // the starting node is incompatible with the filter function of the walker.
 const SKIP_TO_PARENT = "SKIP_TO_PARENT";
 const SKIP_TO_SIBLING = "SKIP_TO_SIBLING";
 
-// The possible completions to a ':' with added score to give certain values
-// some preference.
-const PSEUDO_SELECTORS = [
-  [":active", 1],
-  [":hover", 1],
-  [":focus", 1],
-  [":visited", 0],
-  [":link", 0],
-  [":first-letter", 0],
-  [":first-child", 2],
-  [":before", 2],
-  [":after", 2],
-  [":lang(", 0],
-  [":not(", 3],
-  [":first-of-type", 0],
-  [":last-of-type", 0],
-  [":only-of-type", 0],
-  [":only-child", 2],
-  [":nth-child(", 3],
-  [":nth-last-child(", 0],
-  [":nth-of-type(", 0],
-  [":nth-last-of-type(", 0],
-  [":last-child", 2],
-  [":root", 0],
-  [":empty", 0],
-  [":target", 0],
-  [":enabled", 0],
-  [":disabled", 0],
-  [":checked", 1],
-  ["::selection", 0]
-];
-
-var HELPER_SHEET = "data:text/css;charset=utf-8," + encodeURIComponent(`
-  .__fx-devtools-hide-shortcut__ {
-    visibility: hidden !important;
-  }
-
-  :-moz-devtools-highlighted {
-    outline: 2px dashed #F06!important;
-    outline-offset: -2px !important;
-  }
-`);
-
-/**
- * We only send nodeValue up to a certain size by default.  This stuff
- * controls that size.
- */
-exports.DEFAULT_VALUE_SUMMARY_LENGTH = 50;
-var gValueSummaryLength = exports.DEFAULT_VALUE_SUMMARY_LENGTH;
-
-exports.getValueSummaryLength = function () {
-  return gValueSummaryLength;
-};
-
-exports.setValueSummaryLength = function (val) {
-  gValueSummaryLength = val;
-};
-
-/**
- * Returns the properly cased version of the node's tag name, which can be
- * used when displaying said name in the UI.
- *
- * @param  {Node} rawNode
- *         Node for which we want the display name
- * @return {String}
- *         Properly cased version of the node tag name
- */
-const getNodeDisplayName = function (rawNode) {
-  if (rawNode.nodeName && !rawNode.localName) {
-    // The localName & prefix APIs have been moved from the Node interface to the Element
-    // interface. Use Node.nodeName as a fallback.
-    return rawNode.nodeName;
-  }
-  return (rawNode.prefix ? rawNode.prefix + ":" : "") + rawNode.localName;
-};
-exports.getNodeDisplayName = getNodeDisplayName;
-
-/**
- * Server side of the node actor.
- */
-var NodeActor = exports.NodeActor = protocol.ActorClassWithSpec(nodeSpec, {
-  initialize: function (walker, node) {
-    protocol.Actor.prototype.initialize.call(this, null);
-    this.walker = walker;
-    this.rawNode = node;
-    this._eventParsers = new EventParsers().parsers;
-
-    // Storing the original display of the node, to track changes when reflows
-    // occur
-    this.wasDisplayed = this.isDisplayed;
-  },
-
-  toString: function () {
-    return "[NodeActor " + this.actorID + " for " +
-      this.rawNode.toString() + "]";
-  },
-
-  /**
-   * Instead of storing a connection object, the NodeActor gets its connection
-   * from its associated walker.
-   */
-  get conn() {
-    return this.walker.conn;
-  },
-
-  isDocumentElement: function () {
-    return this.rawNode.ownerDocument &&
-           this.rawNode.ownerDocument.documentElement === this.rawNode;
-  },
-
-  destroy: function () {
-    protocol.Actor.prototype.destroy.call(this);
-
-    if (this.mutationObserver) {
-      if (!Cu.isDeadWrapper(this.mutationObserver)) {
-        this.mutationObserver.disconnect();
-      }
-      this.mutationObserver = null;
-    }
-    this.rawNode = null;
-    this.walker = null;
-  },
-
-  // Returns the JSON representation of this object over the wire.
-  form: function (detail) {
-    if (detail === "actorid") {
-      return this.actorID;
-    }
-
-    let parentNode = this.walker.parentNode(this);
-    let inlineTextChild = this.walker.inlineTextChild(this);
-
-    let form = {
-      actor: this.actorID,
-      baseURI: this.rawNode.baseURI,
-      parent: parentNode ? parentNode.actorID : undefined,
-      nodeType: this.rawNode.nodeType,
-      namespaceURI: this.rawNode.namespaceURI,
-      nodeName: this.rawNode.nodeName,
-      nodeValue: this.rawNode.nodeValue,
-      displayName: getNodeDisplayName(this.rawNode),
-      numChildren: this.numChildren,
-      inlineTextChild: inlineTextChild ? inlineTextChild.form() : undefined,
-
-      // doctype attributes
-      name: this.rawNode.name,
-      publicId: this.rawNode.publicId,
-      systemId: this.rawNode.systemId,
-
-      attrs: this.writeAttrs(),
-      isBeforePseudoElement: this.isBeforePseudoElement,
-      isAfterPseudoElement: this.isAfterPseudoElement,
-      isAnonymous: isAnonymous(this.rawNode),
-      isNativeAnonymous: isNativeAnonymous(this.rawNode),
-      isXBLAnonymous: isXBLAnonymous(this.rawNode),
-      isShadowAnonymous: isShadowAnonymous(this.rawNode),
-      pseudoClassLocks: this.writePseudoClassLocks(),
-
-      isDisplayed: this.isDisplayed,
-      isInHTMLDocument: this.rawNode.ownerDocument &&
-        this.rawNode.ownerDocument.contentType === "text/html",
-      hasEventListeners: this._hasEventListeners,
-    };
-
-    if (this.isDocumentElement()) {
-      form.isDocumentElement = true;
-    }
-
-    // Add an extra API for custom properties added by other
-    // modules/extensions.
-    form.setFormProperty = (name, value) => {
-      if (!form.props) {
-        form.props = {};
-      }
-      form.props[name] = value;
-    };
-
-    // Fire an event so, other modules can create its own properties
-    // that should be passed to the client (within the form.props field).
-    EventEmitter.emit(NodeActor, "form", {
-      target: this,
-      data: form
-    });
-
-    return form;
-  },
-
-  /**
-   * Watch the given document node for mutations using the DOM observer
-   * API.
-   */
-  watchDocument: function (callback) {
-    let node = this.rawNode;
-    // Create the observer on the node's actor.  The node will make sure
-    // the observer is cleaned up when the actor is released.
-    let observer = new node.defaultView.MutationObserver(callback);
-    observer.mergeAttributeRecords = true;
-    observer.observe(node, {
-      nativeAnonymousChildList: true,
-      attributes: true,
-      characterData: true,
-      characterDataOldValue: true,
-      childList: true,
-      subtree: true
-    });
-    this.mutationObserver = observer;
-  },
-
-  get isBeforePseudoElement() {
-    return this.rawNode.nodeName === "_moz_generated_content_before";
-  },
-
-  get isAfterPseudoElement() {
-    return this.rawNode.nodeName === "_moz_generated_content_after";
-  },
-
-  // Estimate the number of children that the walker will return without making
-  // a call to children() if possible.
-  get numChildren() {
-    // For pseudo elements, childNodes.length returns 1, but the walker
-    // will return 0.
-    if (this.isBeforePseudoElement || this.isAfterPseudoElement) {
-      return 0;
-    }
-
-    let rawNode = this.rawNode;
-    let numChildren = rawNode.childNodes.length;
-    let hasAnonChildren = rawNode.nodeType === Ci.nsIDOMNode.ELEMENT_NODE &&
-                          rawNode.ownerDocument.getAnonymousNodes(rawNode);
-
-    let hasContentDocument = rawNode.contentDocument;
-    let hasSVGDocument = rawNode.getSVGDocument && rawNode.getSVGDocument();
-    if (numChildren === 0 && (hasContentDocument || hasSVGDocument)) {
-      // This might be an iframe with virtual children.
-      numChildren = 1;
-    }
-
-    // Normal counting misses ::before/::after.  Also, some anonymous children
-    // may ultimately be skipped, so we have to consult with the walker.
-    if (numChildren === 0 || hasAnonChildren) {
-      numChildren = this.walker.children(this).nodes.length;
-    }
-
-    return numChildren;
-  },
-
-  get computedStyle() {
-    return CssLogic.getComputedStyle(this.rawNode);
-  },
-
-  /**
-   * Is the node's display computed style value other than "none"
-   */
-  get isDisplayed() {
-    // Consider all non-element nodes as displayed.
-    if (isNodeDead(this) ||
-        this.rawNode.nodeType !== Ci.nsIDOMNode.ELEMENT_NODE ||
-        this.isAfterPseudoElement ||
-        this.isBeforePseudoElement) {
-      return true;
-    }
-
-    let style = this.computedStyle;
-    if (!style) {
-      return true;
-    }
-
-    return style.display !== "none";
-  },
-
-  /**
-   * Are there event listeners that are listening on this node? This method
-   * uses all parsers registered via event-parsers.js.registerEventParser() to
-   * check if there are any event listeners.
-   */
-  get _hasEventListeners() {
-    let parsers = this._eventParsers;
-    for (let [, {hasListeners}] of parsers) {
-      try {
-        if (hasListeners && hasListeners(this.rawNode)) {
-          return true;
-        }
-      } catch (e) {
-        // An object attached to the node looked like a listener but wasn't...
-        // do nothing.
-      }
-    }
-    return false;
-  },
-
-  writeAttrs: function () {
-    if (!this.rawNode.attributes) {
-      return undefined;
-    }
-
-    return [...this.rawNode.attributes].map(attr => {
-      return {namespace: attr.namespace, name: attr.name, value: attr.value };
-    });
-  },
-
-  writePseudoClassLocks: function () {
-    if (this.rawNode.nodeType !== Ci.nsIDOMNode.ELEMENT_NODE) {
-      return undefined;
-    }
-    let ret = undefined;
-    for (let pseudo of PSEUDO_CLASSES) {
-      if (InspectorUtils.hasPseudoClassLock(this.rawNode, pseudo)) {
-        ret = ret || [];
-        ret.push(pseudo);
-      }
-    }
-    return ret;
-  },
-
-  /**
-   * Gets event listeners and adds their information to the events array.
-   *
-   * @param  {Node} node
-   *         Node for which we are to get listeners.
-   */
-  getEventListeners: function (node) {
-    let parsers = this._eventParsers;
-    let dbg = this.parent().tabActor.makeDebugger();
-    let listenerArray = [];
-
-    for (let [, {getListeners, normalizeListener}] of parsers) {
-      try {
-        let listeners = getListeners(node);
-
-        if (!listeners) {
-          continue;
-        }
-
-        for (let listener of listeners) {
-          if (normalizeListener) {
-            listener.normalizeListener = normalizeListener;
-          }
-
-          this.processHandlerForEvent(node, listenerArray, dbg, listener);
-        }
-      } catch (e) {
-        // An object attached to the node looked like a listener but wasn't...
-        // do nothing.
-      }
-    }
-
-    listenerArray.sort((a, b) => {
-      return a.type.localeCompare(b.type);
-    });
-
-    return listenerArray;
-  },
-
-  /**
-   * Process a handler
-   *
-   * @param  {Node} node
-   *         The node for which we want information.
-   * @param  {Array} listenerArray
-   *         listenerArray contains all event objects that we have gathered
-   *         so far.
-   * @param  {Debugger} dbg
-   *         JSDebugger instance.
-   * @param  {Object} eventInfo
-   *         See event-parsers.js.registerEventParser() for a description of the
-   *         eventInfo object.
-   *
-   * @return {Array}
-   *         An array of objects where a typical object looks like this:
-   *           {
-   *             type: "click",
-   *             handler: function() { doSomething() },
-   *             origin: "http://www.mozilla.com",
-   *             searchString: 'onclick="doSomething()"',
-   *             tags: tags,
-   *             DOM0: true,
-   *             capturing: true,
-   *             hide: {
-   *               DOM0: true
-   *             },
-   *             native: false
-   *           }
-   */
-  processHandlerForEvent: function (node, listenerArray, dbg, listener) {
-    let { handler } = listener;
-    let global = Cu.getGlobalForObject(handler);
-    let globalDO = dbg.addDebuggee(global);
-    let listenerDO = globalDO.makeDebuggeeValue(handler);
-
-    let { normalizeListener } = listener;
-
-    if (normalizeListener) {
-      listenerDO = normalizeListener(listenerDO, listener);
-    }
-
-    let { capturing } = listener;
-    let dom0 = false;
-    let functionSource = handler.toString();
-    let hide = listener.hide || {};
-    let line = 0;
-    let native = false;
-    let override = listener.override || {};
-    let tags = listener.tags || "";
-    let type = listener.type || "";
-    let url = "";
-
-    // If the listener is an object with a 'handleEvent' method, use that.
-    if (listenerDO.class === "Object" || listenerDO.class === "XULElement") {
-      let desc;
-
-      while (!desc && listenerDO) {
-        desc = listenerDO.getOwnPropertyDescriptor("handleEvent");
-        listenerDO = listenerDO.proto;
-      }
-
-      if (desc && desc.value) {
-        listenerDO = desc.value;
-      }
-    }
-
-    // If the listener is bound to a different context then we need to switch
-    // to the bound function.
-    if (listenerDO.isBoundFunction) {
-      listenerDO = listenerDO.boundTargetFunction;
-    }
-
-    let { isArrowFunction, name, script, parameterNames } = listenerDO;
-
-    if (script) {
-      let scriptSource = script.source.text;
-
-      // Scripts are provided via script tags. If it wasn't provided by a
-      // script tag it must be a DOM0 event.
-      if (script.source.element) {
-        dom0 = script.source.element.class !== "HTMLScriptElement";
-      } else {
-        dom0 = false;
-      }
-
-      line = script.startLine;
-      url = script.url;
-
-      // Checking for the string "[native code]" is the only way at this point
-      // to check for native code. Even if this provides a false positive then
-      // grabbing the source code a second time is harmless.
-      if (functionSource === "[object Object]" ||
-          functionSource === "[object XULElement]" ||
-          functionSource.includes("[native code]")) {
-        functionSource =
-          scriptSource.substr(script.sourceStart, script.sourceLength);
-
-        // At this point the script looks like this:
-        // () { ... }
-        // We prefix this with "function" if it is not a fat arrow function.
-        if (!isArrowFunction) {
-          functionSource = "function " + functionSource;
-        }
-      }
-    } else {
-      // If the listener is a native one (provided by C++ code) then we have no
-      // access to the script. We use the native flag to prevent showing the
-      // debugger button because the script is not available.
-      native = true;
-    }
-
-    // Fat arrow function text always contains the parameters. Function
-    // parameters are often missing e.g. if Array.sort is used as a handler.
-    // If they are missing we provide the parameters ourselves.
-    if (parameterNames && parameterNames.length > 0) {
-      let prefix = "function " + name + "()";
-      let paramString = parameterNames.join(", ");
-
-      if (functionSource.startsWith(prefix)) {
-        functionSource = functionSource.substr(prefix.length);
-
-        functionSource = `function ${name} (${paramString})${functionSource}`;
-      }
-    }
-
-    // If the listener is native code we display the filename "[native code]."
-    // This is the official string and should *not* be translated.
-    let origin;
-    if (native) {
-      origin = "[native code]";
-    } else {
-      origin = url + ((dom0 || line === 0) ? "" : ":" + line);
-    }
-
-    let eventObj = {
-      type: override.type || type,
-      handler: override.handler || functionSource.trim(),
-      origin: override.origin || origin,
-      tags: override.tags || tags,
-      DOM0: typeof override.dom0 !== "undefined" ? override.dom0 : dom0,
-      capturing: typeof override.capturing !== "undefined" ?
-                 override.capturing : capturing,
-      hide: typeof override.hide !== "undefined" ? override.hide : hide,
-      native
-    };
-
-    // Hide the debugger icon for DOM0 and native listeners. DOM0 listeners are
-    // generated dynamically from e.g. an onclick="" attribute so the script
-    // doesn't actually exist.
-    if (native || dom0) {
-      eventObj.hide.debugger = true;
-    }
-
-    listenerArray.push(eventObj);
-
-    dbg.removeDebuggee(globalDO);
-  },
-
-  /**
-   * Returns a LongStringActor with the node's value.
-   */
-  getNodeValue: function () {
-    return new LongStringActor(this.conn, this.rawNode.nodeValue || "");
-  },
-
-  /**
-   * Set the node's value to a given string.
-   */
-  setNodeValue: function (value) {
-    this.rawNode.nodeValue = value;
-  },
-
-  /**
-   * Get a unique selector string for this node.
-   */
-  getUniqueSelector: function () {
-    if (Cu.isDeadWrapper(this.rawNode)) {
-      return "";
-    }
-    return findCssSelector(this.rawNode);
-  },
-
-  /**
-   * Get the full CSS path for this node.
-   *
-   * @return {String} A CSS selector with a part for the node and each of its ancestors.
-   */
-  getCssPath: function () {
-    if (Cu.isDeadWrapper(this.rawNode)) {
-      return "";
-    }
-    return getCssPath(this.rawNode);
-  },
-
-  /**
-   * Get the XPath for this node.
-   *
-   * @return {String} The XPath for finding this node on the page.
-   */
-  getXPath: function () {
-    if (Cu.isDeadWrapper(this.rawNode)) {
-      return "";
-    }
-    return getXPath(this.rawNode);
-  },
-
-  /**
-   * Scroll the selected node into view.
-   */
-  scrollIntoView: function () {
-    this.rawNode.scrollIntoView(true);
-  },
-
-  /**
-   * Get the node's image data if any (for canvas and img nodes).
-   * Returns an imageData object with the actual data being a LongStringActor
-   * and a size json object.
-   * The image data is transmitted as a base64 encoded png data-uri.
-   * The method rejects if the node isn't an image or if the image is missing
-   *
-   * Accepts a maxDim request parameter to resize images that are larger. This
-   * is important as the resizing occurs server-side so that image-data being
-   * transfered in the longstring back to the client will be that much smaller
-   */
-  getImageData: function (maxDim) {
-    return imageToImageData(this.rawNode, maxDim).then(imageData => {
-      return {
-        data: LongStringActor(this.conn, imageData.data),
-        size: imageData.size
-      };
-    });
-  },
-
-  /**
-   * Get all event listeners that are listening on this node.
-   */
-  getEventListenerInfo: function () {
-    let node = this.rawNode;
-
-    if (this.rawNode.nodeName.toLowerCase() === "html") {
-      let winListeners = this.getEventListeners(node.ownerGlobal) || [];
-      let docElementListeners = this.getEventListeners(node) || [];
-      let docListeners = this.getEventListeners(node.parentNode) || [];
-
-      return [...winListeners, ...docElementListeners, ...docListeners];
-    }
-    return this.getEventListeners(node);
-  },
-
-  /**
-   * Modify a node's attributes.  Passed an array of modifications
-   * similar in format to "attributes" mutations.
-   * {
-   *   attributeName: <string>
-   *   attributeNamespace: <optional string>
-   *   newValue: <optional string> - If null or undefined, the attribute
-   *     will be removed.
-   * }
-   *
-   * Returns when the modifications have been made.  Mutations will
-   * be queued for any changes made.
-   */
-  modifyAttributes: function (modifications) {
-    let rawNode = this.rawNode;
-    for (let change of modifications) {
-      if (change.newValue == null) {
-        if (change.attributeNamespace) {
-          rawNode.removeAttributeNS(change.attributeNamespace,
-                                    change.attributeName);
-        } else {
-          rawNode.removeAttribute(change.attributeName);
-        }
-      } else if (change.attributeNamespace) {
-        rawNode.setAttributeNS(change.attributeNamespace, change.attributeName,
-                               change.newValue);
-      } else {
-        rawNode.setAttribute(change.attributeName, change.newValue);
-      }
-    }
-  },
-
-  /**
-   * Given the font and fill style, get the image data of a canvas with the
-   * preview text and font.
-   * Returns an imageData object with the actual data being a LongStringActor
-   * and the width of the text as a string.
-   * The image data is transmitted as a base64 encoded png data-uri.
-   */
-  getFontFamilyDataURL: function (font, fillStyle = "black") {
-    let doc = this.rawNode.ownerDocument;
-    let options = {
-      previewText: FONT_FAMILY_PREVIEW_TEXT,
-      previewFontSize: FONT_FAMILY_PREVIEW_TEXT_SIZE,
-      fillStyle: fillStyle
-    };
-    let { dataURL, size } = getFontPreviewData(font, doc, options);
-
-    return { data: LongStringActor(this.conn, dataURL), size: size };
-  },
-
-  /**
-   * Finds the computed background color of the closest parent with
-   * a set background color.
-   * Returns a string with the background color of the form
-   * rgba(r, g, b, a). Defaults to rgba(255, 255, 255, 1) if no
-   * background color is found.
-   */
-  getClosestBackgroundColor: function () {
-    let current = this.rawNode;
-    while (current) {
-      let computedStyle = CssLogic.getComputedStyle(current);
-      let currentStyle = computedStyle.getPropertyValue("background-color");
-      if (colorUtils.isValidCSSColor(currentStyle)) {
-        let currentCssColor = new colorUtils.CssColor(currentStyle);
-        if (!currentCssColor.isTransparent()) {
-          return currentCssColor.rgba;
-        }
-      }
-      current = current.parentNode;
-    }
-    return "rgba(255, 255, 255, 1)";
-  }
-});
-
-/**
- * Server side of a node list as returned by querySelectorAll()
- */
-var NodeListActor = exports.NodeListActor = protocol.ActorClassWithSpec(nodeListSpec, {
-  typeName: "domnodelist",
-
-  initialize: function (walker, nodeList) {
-    protocol.Actor.prototype.initialize.call(this);
-    this.walker = walker;
-    this.nodeList = nodeList || [];
-  },
-
-  destroy: function () {
-    protocol.Actor.prototype.destroy.call(this);
-  },
-
-  /**
-   * Instead of storing a connection object, the NodeActor gets its connection
-   * from its associated walker.
-   */
-  get conn() {
-    return this.walker.conn;
-  },
-
-  /**
-   * Items returned by this actor should belong to the parent walker.
-   */
-  marshallPool: function () {
-    return this.walker;
-  },
-
-  // Returns the JSON representation of this object over the wire.
-  form: function () {
-    return {
-      actor: this.actorID,
-      length: this.nodeList ? this.nodeList.length : 0
-    };
-  },
-
-  /**
-   * Get a single node from the node list.
-   */
-  item: function (index) {
-    return this.walker.attachElement(this.nodeList[index]);
-  },
-
-  /**
-   * Get a range of the items from the node list.
-   */
-  items: function (start = 0, end = this.nodeList.length) {
-    let items = Array.prototype.slice.call(this.nodeList, start, end)
-      .map(item => this.walker._ref(item));
-    return this.walker.attachElements(items);
-  },
-
-  release: function () {}
-});
-
-/**
- * Server side of the DOM walker.
- */
-var WalkerActor = protocol.ActorClassWithSpec(walkerSpec, {
-  /**
-   * Create the WalkerActor
-   * @param DebuggerServerConnection conn
-   *    The server connection.
-   */
-  initialize: function (conn, tabActor, options) {
-    protocol.Actor.prototype.initialize.call(this, conn);
-    this.tabActor = tabActor;
-    this.rootWin = tabActor.window;
-    this.rootDoc = this.rootWin.document;
-    this._refMap = new Map();
-    this._pendingMutations = [];
-    this._activePseudoClassLocks = new Set();
-    this.showAllAnonymousContent = options.showAllAnonymousContent;
-
-    this.walkerSearch = new WalkerSearch(this);
-
-    // Nodes which have been removed from the client's known
-    // ownership tree are considered "orphaned", and stored in
-    // this set.
-    this._orphaned = new Set();
-
-    // The client can tell the walker that it is interested in a node
-    // even when it is orphaned with the `retainNode` method.  This
-    // list contains orphaned nodes that were so retained.
-    this._retainedOrphans = new Set();
-
-    this.onMutations = this.onMutations.bind(this);
-    this.onFrameLoad = this.onFrameLoad.bind(this);
-    this.onFrameUnload = this.onFrameUnload.bind(this);
-    this._throttledEmitNewMutations = throttle(this._emitNewMutations.bind(this),
-      MUTATIONS_THROTTLING_DELAY);
-
-    tabActor.on("will-navigate", this.onFrameUnload);
-    tabActor.on("window-ready", this.onFrameLoad);
-
-    // Ensure that the root document node actor is ready and
-    // managed.
-    this.rootNode = this.document();
-
-    this.layoutChangeObserver = getLayoutChangesObserver(this.tabActor);
-    this._onReflows = this._onReflows.bind(this);
-    this.layoutChangeObserver.on("reflows", this._onReflows);
-    this._onResize = this._onResize.bind(this);
-    this.layoutChangeObserver.on("resize", this._onResize);
-
-    this._onEventListenerChange = this._onEventListenerChange.bind(this);
-    eventListenerService.addListenerChangeListener(this._onEventListenerChange);
-  },
-
-  /**
-   * Callback for eventListenerService.addListenerChangeListener
-   * @param nsISimpleEnumerator changesEnum
-   *    enumerator of nsIEventListenerChange
-   */
-  _onEventListenerChange: function (changesEnum) {
-    let changes = changesEnum.enumerate();
-    while (changes.hasMoreElements()) {
-      let current = changes.getNext().QueryInterface(Ci.nsIEventListenerChange);
-      let target = current.target;
-
-      if (this._refMap.has(target)) {
-        let actor = this.getNode(target);
-        let mutation = {
-          type: "events",
-          target: actor.actorID,
-          hasEventListeners: actor._hasEventListeners
-        };
-        this.queueMutation(mutation);
-      }
-    }
-  },
-
-  // Returns the JSON representation of this object over the wire.
-  form: function () {
-    return {
-      actor: this.actorID,
-      root: this.rootNode.form(),
-      traits: {
-        // FF42+ Inspector starts managing the Walker, while the inspector also
-        // starts cleaning itself up automatically on client disconnection.
-        // So that there is no need to manually release the walker anymore.
-        autoReleased: true,
-        // XXX: It seems silly that we need to tell the front which capabilities
-        // its actor has in this way when the target can use actorHasMethod. If
-        // this was ported to the protocol (Bug 1157048) we could call that
-        // inside of custom front methods and not need to do traits for this.
-        multiFrameQuerySelectorAll: true,
-        textSearch: true,
-      }
-    };
-  },
-
-  toString: function () {
-    return "[WalkerActor " + this.actorID + "]";
-  },
-
-  getDocumentWalker: function (node, whatToShow, skipTo) {
-    // Allow native anon content (like <video> controls) if preffed on
-    let nodeFilter = this.showAllAnonymousContent
-                    ? allAnonymousContentTreeWalkerFilter
-                    : standardTreeWalkerFilter;
-    return new DocumentWalker(node, this.rootWin, whatToShow, nodeFilter, skipTo);
-  },
-
-  destroy: function () {
-    if (this._destroyed) {
-      return;
-    }
-    this._destroyed = true;
-    protocol.Actor.prototype.destroy.call(this);
-    try {
-      this.clearPseudoClassLocks();
-      this._activePseudoClassLocks = null;
-
-      this._hoveredNode = null;
-      this.rootWin = null;
-      this.rootDoc = null;
-      this.rootNode = null;
-      this.layoutHelpers = null;
-      this._orphaned = null;
-      this._retainedOrphans = null;
-      this._refMap = null;
-
-      this.tabActor.off("will-navigate", this.onFrameUnload);
-      this.tabActor.off("window-ready", this.onFrameLoad);
-
-      this.onFrameLoad = null;
-      this.onFrameUnload = null;
-
-      this.walkerSearch.destroy();
-
-      this.layoutChangeObserver.off("reflows", this._onReflows);
-      this.layoutChangeObserver.off("resize", this._onResize);
-      this.layoutChangeObserver = null;
-      releaseLayoutChangesObserver(this.tabActor);
-
-      eventListenerService.removeListenerChangeListener(
-        this._onEventListenerChange);
-
-      this.onMutations = null;
-
-      this.layoutActor = null;
-      this.tabActor = null;
-
-      this.emit("destroyed");
-    } catch (e) {
-      console.error(e);
-    }
-  },
-
-  release: function () {},
-
-  unmanage: function (actor) {
-    if (actor instanceof NodeActor) {
-      if (this._activePseudoClassLocks &&
-          this._activePseudoClassLocks.has(actor)) {
-        this.clearPseudoClassLocks(actor);
-      }
-      this._refMap.delete(actor.rawNode);
-    }
-    protocol.Actor.prototype.unmanage.call(this, actor);
-  },
-
-  /**
-   * Determine if the walker has come across this DOM node before.
-   * @param {DOMNode} rawNode
-   * @return {Boolean}
-   */
-  hasNode: function (rawNode) {
-    return this._refMap.has(rawNode);
-  },
-
-  /**
-   * If the walker has come across this DOM node before, then get the
-   * corresponding node actor.
-   * @param {DOMNode} rawNode
-   * @return {NodeActor}
-   */
-  getNode: function (rawNode) {
-    return this._refMap.get(rawNode);
-  },
-
-  _ref: function (node) {
-    let actor = this.getNode(node);
-    if (actor) {
-      return actor;
-    }
-
-    actor = new NodeActor(this, node);
-
-    // Add the node actor as a child of this walker actor, assigning
-    // it an actorID.
-    this.manage(actor);
-    this._refMap.set(node, actor);
-
-    if (node.nodeType === Ci.nsIDOMNode.DOCUMENT_NODE) {
-      actor.watchDocument(this.onMutations);
-    }
-    return actor;
-  },
-
-  _onReflows: function (reflows) {
-    // Going through the nodes the walker knows about, see which ones have
-    // had their display changed and send a display-change event if any
-    let changes = [];
-    for (let [node, actor] of this._refMap) {
-      if (Cu.isDeadWrapper(node)) {
-        continue;
-      }
-
-      let isDisplayed = actor.isDisplayed;
-      if (isDisplayed !== actor.wasDisplayed) {
-        changes.push(actor);
-        // Updating the original value
-        actor.wasDisplayed = isDisplayed;
-      }
-    }
-
-    if (changes.length) {
-      this.emit("display-change", changes);
-    }
-  },
-
-  /**
-   * When the browser window gets resized, relay the event to the front.
-   */
-  _onResize: function () {
-    this.emit("resize");
-  },
-
-  /**
-   * This is kept for backward-compatibility reasons with older remote targets.
-   * Targets prior to bug 916443.
-   *
-   * pick/cancelPick are used to pick a node on click on the content
-   * document. But in their implementation prior to bug 916443, they don't allow
-   * highlighting on hover.
-   * The client-side now uses the highlighter actor's pick and cancelPick
-   * methods instead. The client-side uses the the highlightable trait found in
-   * the root actor to determine which version of pick to use.
-   *
-   * As for highlight, the new highlighter actor is used instead of the walker's
-   * highlight method. Same here though, the client-side uses the highlightable
-   * trait to dertermine which to use.
-   *
-   * Keeping these actor methods for now allows newer client-side debuggers to
-   * inspect fxos 1.2 remote targets or older firefox desktop remote targets.
-   */
-  pick: function () {},
-  cancelPick: function () {},
-  highlight: function (node) {},
-
-  /**
-   * Ensures that the node is attached and it can be accessed from the root.
-   *
-   * @param {(Node|NodeActor)} nodes The nodes
-   * @return {Object} An object compatible with the disconnectedNode type.
-   */
-  attachElement: function (node) {
-    let { nodes, newParents } = this.attachElements([node]);
-    return {
-      node: nodes[0],
-      newParents: newParents
-    };
-  },
-
-  /**
-   * Ensures that the nodes are attached and they can be accessed from the root.
-   *
-   * @param {(Node[]|NodeActor[])} nodes The nodes
-   * @return {Object} An object compatible with the disconnectedNodeArray type.
-   */
-  attachElements: function (nodes) {
-    let nodeActors = [];
-    let newParents = new Set();
-    for (let node of nodes) {
-      if (!(node instanceof NodeActor)) {
-        // If an anonymous node was passed in and we aren't supposed to know
-        // about it, then consult with the document walker as the source of
-        // truth about which elements exist.
-        if (!this.showAllAnonymousContent && isAnonymous(node)) {
-          node = this.getDocumentWalker(node).currentNode;
-        }
-
-        node = this._ref(node);
-      }
-
-      this.ensurePathToRoot(node, newParents);
-      // If nodes may be an array of raw nodes, we're sure to only have
-      // NodeActors with the following array.
-      nodeActors.push(node);
-    }
-
-    return {
-      nodes: nodeActors,
-      newParents: [...newParents]
-    };
-  },
-
-  /**
-   * Return the document node that contains the given node,
-   * or the root node if no node is specified.
-   * @param NodeActor node
-   *        The node whose document is needed, or null to
-   *        return the root.
-   */
-  document: function (node) {
-    let doc = isNodeDead(node) ? this.rootDoc : nodeDocument(node.rawNode);
-    return this._ref(doc);
-  },
-
-  /**
-   * Return the documentElement for the document containing the
-   * given node.
-   * @param NodeActor node
-   *        The node whose documentElement is requested, or null
-   *        to use the root document.
-   */
-  documentElement: function (node) {
-    let elt = isNodeDead(node)
-              ? this.rootDoc.documentElement
-              : nodeDocument(node.rawNode).documentElement;
-    return this._ref(elt);
-  },
-
-  /**
-   * Return all parents of the given node, ordered from immediate parent
-   * to root.
-   * @param NodeActor node
-   *    The node whose parents are requested.
-   * @param object options
-   *    Named options, including:
-   *    `sameDocument`: If true, parents will be restricted to the same
-   *      document as the node.
-   *    `sameTypeRootTreeItem`: If true, this will not traverse across
-   *     different types of docshells.
-   */
-  parents: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return [];
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let parents = [];
-    let cur;
-    while ((cur = walker.parentNode())) {
-      if (options.sameDocument &&
-          nodeDocument(cur) != nodeDocument(node.rawNode)) {
-        break;
-      }
-
-      if (options.sameTypeRootTreeItem &&
-          nodeDocshell(cur).sameTypeRootTreeItem !=
-          nodeDocshell(node.rawNode).sameTypeRootTreeItem) {
-        break;
-      }
-
-      parents.push(this._ref(cur));
-    }
-    return parents;
-  },
-
-  parentNode: function (node) {
-    let walker = this.getDocumentWalker(node.rawNode);
-    let parent = walker.parentNode();
-    if (parent) {
-      return this._ref(parent);
-    }
-    return null;
-  },
-
-  /**
-   * If the given NodeActor only has a single text node as a child with a text
-   * content small enough to be inlined, return that child's NodeActor.
-   *
-   * @param NodeActor node
-   */
-  inlineTextChild: function (node) {
-    // Quick checks to prevent creating a new walker if possible.
-    if (node.isBeforePseudoElement ||
-        node.isAfterPseudoElement ||
-        node.rawNode.nodeType != Ci.nsIDOMNode.ELEMENT_NODE ||
-        node.rawNode.children.length > 0) {
-      return undefined;
-    }
-
-    let docWalker = this.getDocumentWalker(node.rawNode);
-    let firstChild = docWalker.firstChild();
-
-    // Bail out if:
-    // - more than one child
-    // - unique child is not a text node
-    // - unique child is a text node, but is too long to be inlined
-    if (!firstChild ||
-        docWalker.nextSibling() ||
-        firstChild.nodeType !== Ci.nsIDOMNode.TEXT_NODE ||
-        firstChild.nodeValue.length > gValueSummaryLength
-        ) {
-      return undefined;
-    }
-
-    return this._ref(firstChild);
-  },
-
-  /**
-   * Mark a node as 'retained'.
-   *
-   * A retained node is not released when `releaseNode` is called on its
-   * parent, or when a parent is released with the `cleanup` option to
-   * `getMutations`.
-   *
-   * When a retained node's parent is released, a retained mode is added to
-   * the walker's "retained orphans" list.
-   *
-   * Retained nodes can be deleted by providing the `force` option to
-   * `releaseNode`.  They will also be released when their document
-   * has been destroyed.
-   *
-   * Retaining a node makes no promise about its children;  They can
-   * still be removed by normal means.
-   */
-  retainNode: function (node) {
-    node.retained = true;
-  },
-
-  /**
-   * Remove the 'retained' mark from a node.  If the node was a
-   * retained orphan, release it.
-   */
-  unretainNode: function (node) {
-    node.retained = false;
-    if (this._retainedOrphans.has(node)) {
-      this._retainedOrphans.delete(node);
-      this.releaseNode(node);
-    }
-  },
-
-  /**
-   * Release actors for a node and all child nodes.
-   */
-  releaseNode: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    if (node.retained && !options.force) {
-      this._retainedOrphans.add(node);
-      return;
-    }
-
-    if (node.retained) {
-      // Forcing a retained node to go away.
-      this._retainedOrphans.delete(node);
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-
-    let child = walker.firstChild();
-    while (child) {
-      let childActor = this.getNode(child);
-      if (childActor) {
-        this.releaseNode(childActor, options);
-      }
-      child = walker.nextSibling();
-    }
-
-    node.destroy();
-  },
-
-  /**
-   * Add any nodes between `node` and the walker's root node that have not
-   * yet been seen by the client.
-   */
-  ensurePathToRoot: function (node, newParents = new Set()) {
-    if (!node) {
-      return newParents;
-    }
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let parent = this.getNode(cur);
-      if (!parent) {
-        // This parent didn't exist, so hasn't been seen by the client yet.
-        newParents.add(this._ref(cur));
-      } else {
-        // This parent did exist, so the client knows about it.
-        return newParents;
-      }
-    }
-    return newParents;
-  },
-
-  /**
-   * Return children of the given node.  By default this method will return
-   * all children of the node, but there are options that can restrict this
-   * to a more manageable subset.
-   *
-   * @param NodeActor node
-   *    The node whose children you're curious about.
-   * @param object options
-   *    Named options:
-   *    `maxNodes`: The set of nodes returned by the method will be no longer
-   *       than maxNodes.
-   *    `start`: If a node is specified, the list of nodes will start
-   *       with the given child.  Mutally exclusive with `center`.
-   *    `center`: If a node is specified, the given node will be as centered
-   *       as possible in the list, given how close to the ends of the child
-   *       list it is.  Mutually exclusive with `start`.
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   *
-   * @returns an object with three items:
-   *    hasFirst: true if the first child of the node is included in the list.
-   *    hasLast: true if the last child of the node is included in the list.
-   *    nodes: Child nodes returned by the request.
-   */
-  children: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    if (options.center && options.start) {
-      throw Error("Can't specify both 'center' and 'start' options.");
-    }
-    let maxNodes = options.maxNodes || -1;
-    if (maxNodes == -1) {
-      maxNodes = Number.MAX_VALUE;
-    }
-
-    // We're going to create a few document walkers with the same filter,
-    // make it easier.
-    let getFilteredWalker = documentWalkerNode => {
-      let { whatToShow } = options;
-      // Use SKIP_TO_SIBLING to force the walker to use a sibling of the provided node
-      // in case this one is incompatible with the walker's filter function.
-      return this.getDocumentWalker(documentWalkerNode, whatToShow, SKIP_TO_SIBLING);
-    };
-
-    // Need to know the first and last child.
-    let rawNode = node.rawNode;
-    let firstChild = getFilteredWalker(rawNode).firstChild();
-    let lastChild = getFilteredWalker(rawNode).lastChild();
-
-    if (!firstChild) {
-      // No children, we're done.
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    let start;
-    if (options.center) {
-      start = options.center.rawNode;
-    } else if (options.start) {
-      start = options.start.rawNode;
-    } else {
-      start = firstChild;
-    }
-
-    let nodes = [];
-
-    // Start by reading backward from the starting point if we're centering...
-    let backwardWalker = getFilteredWalker(start);
-    if (backwardWalker.currentNode != firstChild && options.center) {
-      backwardWalker.previousSibling();
-      let backwardCount = Math.floor(maxNodes / 2);
-      let backwardNodes = this._readBackward(backwardWalker, backwardCount);
-      nodes = backwardNodes;
-    }
-
-    // Then read forward by any slack left in the max children...
-    let forwardWalker = getFilteredWalker(start);
-    let forwardCount = maxNodes - nodes.length;
-    nodes = nodes.concat(this._readForward(forwardWalker, forwardCount));
-
-    // If there's any room left, it means we've run all the way to the end.
-    // If we're centering, check if there are more items to read at the front.
-    let remaining = maxNodes - nodes.length;
-    if (options.center && remaining > 0 && nodes[0].rawNode != firstChild) {
-      let firstNodes = this._readBackward(backwardWalker, remaining);
-
-      // Then put it all back together.
-      nodes = firstNodes.concat(nodes);
-    }
-
-    return {
-      hasFirst: nodes[0].rawNode == firstChild,
-      hasLast: nodes[nodes.length - 1].rawNode == lastChild,
-      nodes: nodes
-    };
-  },
-
-  /**
-   * Return siblings of the given node.  By default this method will return
-   * all siblings of the node, but there are options that can restrict this
-   * to a more manageable subset.
-   *
-   * If `start` or `center` are not specified, this method will center on the
-   * node whose siblings are requested.
-   *
-   * @param NodeActor node
-   *    The node whose children you're curious about.
-   * @param object options
-   *    Named options:
-   *    `maxNodes`: The set of nodes returned by the method will be no longer
-   *       than maxNodes.
-   *    `start`: If a node is specified, the list of nodes will start
-   *       with the given child.  Mutally exclusive with `center`.
-   *    `center`: If a node is specified, the given node will be as centered
-   *       as possible in the list, given how close to the ends of the child
-   *       list it is.  Mutually exclusive with `start`.
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   *
-   * @returns an object with three items:
-   *    hasFirst: true if the first child of the node is included in the list.
-   *    hasLast: true if the last child of the node is included in the list.
-   *    nodes: Child nodes returned by the request.
-   */
-  siblings: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    let parentNode = this.getDocumentWalker(node.rawNode, options.whatToShow)
-                         .parentNode();
-    if (!parentNode) {
-      return {
-        hasFirst: true,
-        hasLast: true,
-        nodes: [node]
-      };
-    }
-
-    if (!(options.start || options.center)) {
-      options.center = node;
-    }
-
-    return this.children(this._ref(parentNode), options);
-  },
-
-  /**
-   * Get the next sibling of a given node.  Getting nodes one at a time
-   * might be inefficient, be careful.
-   *
-   * @param object options
-   *    Named options:
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   */
-  nextSibling: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode, options.whatToShow);
-    let sibling = walker.nextSibling();
-    return sibling ? this._ref(sibling) : null;
-  },
-
-  /**
-   * Get the previous sibling of a given node.  Getting nodes one at a time
-   * might be inefficient, be careful.
-   *
-   * @param object options
-   *    Named options:
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   */
-  previousSibling: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode, options.whatToShow);
-    let sibling = walker.previousSibling();
-    return sibling ? this._ref(sibling) : null;
-  },
-
-  /**
-   * Helper function for the `children` method: Read forward in the sibling
-   * list into an array with `count` items, including the current node.
-   */
-  _readForward: function (walker, count) {
-    let ret = [];
-
-    let node = walker.currentNode;
-    do {
-      if (!walker.isSkippedNode(node)) {
-        // The walker can be on a node that would be filtered out if it didn't find any
-        // other node to fallback to.
-        ret.push(this._ref(node));
-      }
-      node = walker.nextSibling();
-    } while (node && --count);
-    return ret;
-  },
-
-  /**
-   * Helper function for the `children` method: Read backward in the sibling
-   * list into an array with `count` items, including the current node.
-   */
-  _readBackward: function (walker, count) {
-    let ret = [];
-
-    let node = walker.currentNode;
-    do {
-      if (!walker.isSkippedNode(node)) {
-        // The walker can be on a node that would be filtered out if it didn't find any
-        // other node to fallback to.
-        ret.push(this._ref(node));
-      }
-      node = walker.previousSibling();
-    } while (node && --count);
-    ret.reverse();
-    return ret;
-  },
-
-  /**
-   * Return the first node in the document that matches the given selector.
-   * See https://developer.mozilla.org/en-US/docs/Web/API/Element.querySelector
-   *
-   * @param NodeActor baseNode
-   * @param string selector
-   */
-  querySelector: function (baseNode, selector) {
-    if (isNodeDead(baseNode)) {
-      return {};
-    }
-
-    let node = baseNode.rawNode.querySelector(selector);
-    if (!node) {
-      return {};
-    }
-
-    return this.attachElement(node);
-  },
-
-  /**
-   * Return a NodeListActor with all nodes that match the given selector.
-   * See https://developer.mozilla.org/en-US/docs/Web/API/Element.querySelectorAll
-   *
-   * @param NodeActor baseNode
-   * @param string selector
-   */
-  querySelectorAll: function (baseNode, selector) {
-    let nodeList = null;
-
-    try {
-      nodeList = baseNode.rawNode.querySelectorAll(selector);
-    } catch (e) {
-      // Bad selector. Do nothing as the selector can come from a searchbox.
-    }
-
-    return new NodeListActor(this, nodeList);
-  },
-
-  /**
-   * Get a list of nodes that match the given selector in all known frames of
-   * the current content page.
-   * @param {String} selector.
-   * @return {Array}
-   */
-  _multiFrameQuerySelectorAll: function (selector) {
-    let nodes = [];
-
-    for (let {document} of this.tabActor.windows) {
-      try {
-        nodes = [...nodes, ...document.querySelectorAll(selector)];
-      } catch (e) {
-        // Bad selector. Do nothing as the selector can come from a searchbox.
-      }
-    }
-
-    return nodes;
-  },
-
-  /**
-   * Return a NodeListActor with all nodes that match the given selector in all
-   * frames of the current content page.
-   * @param {String} selector
-   */
-  multiFrameQuerySelectorAll: function (selector) {
-    return new NodeListActor(this, this._multiFrameQuerySelectorAll(selector));
-  },
-
-  /**
-   * Search the document for a given string.
-   * Results will be searched with the walker-search module (searches through
-   * tag names, attribute names and values, and text contents).
-   *
-   * @returns {searchresult}
-   *            - {NodeList} list
-   *            - {Array<Object>} metadata. Extra information with indices that
-   *                              match up with node list.
-   */
-  search: function (query) {
-    let results = this.walkerSearch.search(query);
-    let nodeList = new NodeListActor(this, results.map(r => r.node));
-
-    return {
-      list: nodeList,
-      metadata: []
-    };
-  },
-
-  /**
-   * Returns a list of matching results for CSS selector autocompletion.
-   *
-   * @param string query
-   *        The selector query being completed
-   * @param string completing
-   *        The exact token being completed out of the query
-   * @param string selectorState
-   *        One of "pseudo", "id", "tag", "class", "null"
-   */
-  getSuggestionsForQuery: function (query, completing, selectorState) {
-    let sugs = {
-      classes: new Map(),
-      tags: new Map(),
-      ids: new Map()
-    };
-    let result = [];
-    let nodes = null;
-    // Filtering and sorting the results so that protocol transfer is miminal.
-    switch (selectorState) {
-      case "pseudo":
-        result = PSEUDO_SELECTORS.filter(item => {
-          return item[0].startsWith(":" + completing);
-        });
-        break;
-
-      case "class":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("[class]");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          for (let className of node.classList) {
-            sugs.classes.set(className, (sugs.classes.get(className)|0) + 1);
-          }
-        }
-        sugs.classes.delete("");
-        sugs.classes.delete(HIDDEN_CLASS);
-        for (let [className, count] of sugs.classes) {
-          if (className.startsWith(completing)) {
-            result.push(["." + CSS.escape(className), count, selectorState]);
-          }
-        }
-        break;
-
-      case "id":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("[id]");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          sugs.ids.set(node.id, (sugs.ids.get(node.id)|0) + 1);
-        }
-        for (let [id, count] of sugs.ids) {
-          if (id.startsWith(completing) && id !== "") {
-            result.push(["#" + CSS.escape(id), count, selectorState]);
-          }
-        }
-        break;
-
-      case "tag":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("*");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          let tag = node.localName;
-          sugs.tags.set(tag, (sugs.tags.get(tag)|0) + 1);
-        }
-        for (let [tag, count] of sugs.tags) {
-          if ((new RegExp("^" + completing + ".*", "i")).test(tag)) {
-            result.push([tag, count, selectorState]);
-          }
-        }
-
-        // For state 'tag' (no preceding # or .) and when there's no query (i.e.
-        // only one word) then search for the matching classes and ids
-        if (!query) {
-          result = [
-            ...result,
-            ...this.getSuggestionsForQuery(null, completing, "class")
-                   .suggestions,
-            ...this.getSuggestionsForQuery(null, completing, "id")
-                   .suggestions
-          ];
-        }
-
-        break;
-
-      case "null":
-        nodes = this._multiFrameQuerySelectorAll(query);
-        for (let node of nodes) {
-          sugs.ids.set(node.id, (sugs.ids.get(node.id)|0) + 1);
-          let tag = node.localName;
-          sugs.tags.set(tag, (sugs.tags.get(tag)|0) + 1);
-          for (let className of node.classList) {
-            sugs.classes.set(className, (sugs.classes.get(className)|0) + 1);
-          }
-        }
-        for (let [tag, count] of sugs.tags) {
-          tag && result.push([tag, count]);
-        }
-        for (let [id, count] of sugs.ids) {
-          id && result.push(["#" + id, count]);
-        }
-        sugs.classes.delete("");
-        sugs.classes.delete(HIDDEN_CLASS);
-        for (let [className, count] of sugs.classes) {
-          className && result.push(["." + className, count]);
-        }
-    }
-
-    // Sort by count (desc) and name (asc)
-    result = result.sort((a, b) => {
-      // Computed a sortable string with first the inverted count, then the name
-      let sortA = (10000 - a[1]) + a[0];
-      let sortB = (10000 - b[1]) + b[0];
-
-      // Prefixing ids, classes and tags, to group results
-      let firstA = a[0].substring(0, 1);
-      let firstB = b[0].substring(0, 1);
-
-      if (firstA === "#") {
-        sortA = "2" + sortA;
-      } else if (firstA === ".") {
-        sortA = "1" + sortA;
-      } else {
-        sortA = "0" + sortA;
-      }
-
-      if (firstB === "#") {
-        sortB = "2" + sortB;
-      } else if (firstB === ".") {
-        sortB = "1" + sortB;
-      } else {
-        sortB = "0" + sortB;
-      }
-
-      // String compare
-      return sortA.localeCompare(sortB);
-    });
-
-    result.slice(0, 25);
-
-    return {
-      query: query,
-      suggestions: result
-    };
-  },
-
-  /**
-   * Add a pseudo-class lock to a node.
-   *
-   * @param NodeActor node
-   * @param string pseudo
-   *    A pseudoclass: ':hover', ':active', ':focus'
-   * @param options
-   *    Options object:
-   *    `parents`: True if the pseudo-class should be added
-   *      to parent nodes.
-   *    `enabled`: False if the pseudo-class should be locked
-   *      to 'off'. Defaults to true.
-   *
-   * @returns An empty packet.  A "pseudoClassLock" mutation will
-   *    be queued for any changed nodes.
-   */
-  addPseudoClassLock: function (node, pseudo, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    // There can be only one node locked per pseudo, so dismiss all existing
-    // ones
-    for (let locked of this._activePseudoClassLocks) {
-      if (InspectorUtils.hasPseudoClassLock(locked.rawNode, pseudo)) {
-        this._removePseudoClassLock(locked, pseudo);
-      }
-    }
-
-    let enabled = options.enabled === undefined ||
-                  options.enabled;
-    this._addPseudoClassLock(node, pseudo, enabled);
-
-    if (!options.parents) {
-      return;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let curNode = this._ref(cur);
-      this._addPseudoClassLock(curNode, pseudo, enabled);
-    }
-  },
-
-  _queuePseudoClassMutation: function (node) {
-    this.queueMutation({
-      target: node.actorID,
-      type: "pseudoClassLock",
-      pseudoClassLocks: node.writePseudoClassLocks()
-    });
-  },
-
-  _addPseudoClassLock: function (node, pseudo, enabled) {
-    if (node.rawNode.nodeType !== Ci.nsIDOMNode.ELEMENT_NODE) {
-      return false;
-    }
-    InspectorUtils.addPseudoClassLock(node.rawNode, pseudo, enabled);
-    this._activePseudoClassLocks.add(node);
-    this._queuePseudoClassMutation(node);
-    return true;
-  },
-
-  hideNode: function (node) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    loadSheet(node.rawNode.ownerGlobal, HELPER_SHEET);
-    node.rawNode.classList.add(HIDDEN_CLASS);
-  },
-
-  unhideNode: function (node) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    node.rawNode.classList.remove(HIDDEN_CLASS);
-  },
-
-  /**
-   * Remove a pseudo-class lock from a node.
-   *
-   * @param NodeActor node
-   * @param string pseudo
-   *    A pseudoclass: ':hover', ':active', ':focus'
-   * @param options
-   *    Options object:
-   *    `parents`: True if the pseudo-class should be removed
-   *      from parent nodes.
-   *
-   * @returns An empty response.  "pseudoClassLock" mutations
-   *    will be emitted for any changed nodes.
-   */
-  removePseudoClassLock: function (node, pseudo, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    this._removePseudoClassLock(node, pseudo);
-
-    // Remove pseudo class for children as we don't want to allow
-    // turning it on for some childs without setting it on some parents
-    for (let locked of this._activePseudoClassLocks) {
-      if (node.rawNode.contains(locked.rawNode) &&
-          InspectorUtils.hasPseudoClassLock(locked.rawNode, pseudo)) {
-        this._removePseudoClassLock(locked, pseudo);
-      }
-    }
-
-    if (!options.parents) {
-      return;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let curNode = this._ref(cur);
-      this._removePseudoClassLock(curNode, pseudo);
-    }
-  },
-
-  _removePseudoClassLock: function (node, pseudo) {
-    if (node.rawNode.nodeType != Ci.nsIDOMNode.ELEMENT_NODE) {
-      return false;
-    }
-    InspectorUtils.removePseudoClassLock(node.rawNode, pseudo);
-    if (!node.writePseudoClassLocks()) {
-      this._activePseudoClassLocks.delete(node);
-    }
-
-    this._queuePseudoClassMutation(node);
-    return true;
-  },
-
-  /**
-   * Clear all the pseudo-classes on a given node or all nodes.
-   * @param {NodeActor} node Optional node to clear pseudo-classes on
-   */
-  clearPseudoClassLocks: function (node) {
-    if (node && isNodeDead(node)) {
-      return;
-    }
-
-    if (node) {
-      InspectorUtils.clearPseudoClassLocks(node.rawNode);
-      this._activePseudoClassLocks.delete(node);
-      this._queuePseudoClassMutation(node);
-    } else {
-      for (let locked of this._activePseudoClassLocks) {
-        InspectorUtils.clearPseudoClassLocks(locked.rawNode);
-        this._activePseudoClassLocks.delete(locked);
-        this._queuePseudoClassMutation(locked);
-      }
-    }
-  },
-
-  /**
-   * Get a node's innerHTML property.
-   */
-  innerHTML: function (node) {
-    let html = "";
-    if (!isNodeDead(node)) {
-      html = node.rawNode.innerHTML;
-    }
-    return LongStringActor(this.conn, html);
-  },
-
-  /**
-   * Set a node's innerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   * @param {string} value The piece of HTML content.
-   */
-  setInnerHTML: function (node, value) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    let rawNode = node.rawNode;
-    if (rawNode.nodeType !== rawNode.ownerDocument.ELEMENT_NODE) {
-      throw new Error("Can only change innerHTML to element nodes");
-    }
-    // eslint-disable-next-line no-unsanitized/property
-    rawNode.innerHTML = value;
-  },
-
-  /**
-   * Get a node's outerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   */
-  outerHTML: function (node) {
-    let outerHTML = "";
-    if (!isNodeDead(node)) {
-      outerHTML = node.rawNode.outerHTML;
-    }
-    return LongStringActor(this.conn, outerHTML);
-  },
-
-  /**
-   * Set a node's outerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   * @param {string} value The piece of HTML content.
-   */
-  setOuterHTML: function (node, value) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    let parsedDOM = DOMParser.parseFromString(value, "text/html");
-    let rawNode = node.rawNode;
-    let parentNode = rawNode.parentNode;
-
-    // Special case for head and body.  Setting document.body.outerHTML
-    // creates an extra <head> tag, and document.head.outerHTML creates
-    // an extra <body>.  So instead we will call replaceChild with the
-    // parsed DOM, assuming that they aren't trying to set both tags at once.
-    if (rawNode.tagName === "BODY") {
-      if (parsedDOM.head.innerHTML === "") {
-        parentNode.replaceChild(parsedDOM.body, rawNode);
-      } else {
-      // eslint-disable-next-line no-unsanitized/property
-        rawNode.outerHTML = value;
-      }
-    } else if (rawNode.tagName === "HEAD") {
-      if (parsedDOM.body.innerHTML === "") {
-        parentNode.replaceChild(parsedDOM.head, rawNode);
-      } else {
-        // eslint-disable-next-line no-unsanitized/property
-        rawNode.outerHTML = value;
-      }
-    } else if (node.isDocumentElement()) {
-      // Unable to set outerHTML on the document element.  Fall back by
-      // setting attributes manually, then replace the body and head elements.
-      let finalAttributeModifications = [];
-      let attributeModifications = {};
-      for (let attribute of rawNode.attributes) {
-        attributeModifications[attribute.name] = null;
-      }
-      for (let attribute of parsedDOM.documentElement.attributes) {
-        attributeModifications[attribute.name] = attribute.value;
-      }
-      for (let key in attributeModifications) {
-        finalAttributeModifications.push({
-          attributeName: key,
-          newValue: attributeModifications[key]
-        });
-      }
-      node.modifyAttributes(finalAttributeModifications);
-      rawNode.replaceChild(parsedDOM.head, rawNode.querySelector("head"));
-      rawNode.replaceChild(parsedDOM.body, rawNode.querySelector("body"));
-    } else {
-      // eslint-disable-next-line no-unsanitized/property
-      rawNode.outerHTML = value;
-    }
-  },
-
-  /**
-   * Insert adjacent HTML to a node.
-   *
-   * @param {Node} node
-   * @param {string} position One of "beforeBegin", "afterBegin", "beforeEnd",
-   *                          "afterEnd" (see Element.insertAdjacentHTML).
-   * @param {string} value The HTML content.
-   */
-  insertAdjacentHTML: function (node, position, value) {
-    if (isNodeDead(node)) {
-      return {node: [], newParents: []};
-    }
-
-    let rawNode = node.rawNode;
-    let isInsertAsSibling = position === "beforeBegin" ||
-      position === "afterEnd";
-
-    // Don't insert anything adjacent to the document element.
-    if (isInsertAsSibling && node.isDocumentElement()) {
-      throw new Error("Can't insert adjacent element to the root.");
-    }
-
-    let rawParentNode = rawNode.parentNode;
-    if (!rawParentNode && isInsertAsSibling) {
-      throw new Error("Can't insert as sibling without parent node.");
-    }
-
-    // We can't use insertAdjacentHTML, because we want to return the nodes
-    // being created (so the front can remove them if the user undoes
-    // the change). So instead, use Range.createContextualFragment().
-    let range = rawNode.ownerDocument.createRange();
-    if (position === "beforeBegin" || position === "afterEnd") {
-      range.selectNode(rawNode);
-    } else {
-      range.selectNodeContents(rawNode);
-    }
-    let docFrag = range.createContextualFragment(value);
-    let newRawNodes = Array.from(docFrag.childNodes);
-    switch (position) {
-      case "beforeBegin":
-        rawParentNode.insertBefore(docFrag, rawNode);
-        break;
-      case "afterEnd":
-        // Note: if the second argument is null, rawParentNode.insertBefore
-        // behaves like rawParentNode.appendChild.
-        rawParentNode.insertBefore(docFrag, rawNode.nextSibling);
-        break;
-      case "afterBegin":
-        rawNode.insertBefore(docFrag, rawNode.firstChild);
-        break;
-      case "beforeEnd":
-        rawNode.appendChild(docFrag);
-        break;
-      default:
-        throw new Error("Invalid position value. Must be either " +
-          "'beforeBegin', 'beforeEnd', 'afterBegin' or 'afterEnd'.");
-    }
-
-    return this.attachElements(newRawNodes);
-  },
-
-  /**
-   * Duplicate a specified node
-   *
-   * @param {NodeActor} node The node to duplicate.
-   */
-  duplicateNode: function ({rawNode}) {
-    let clonedNode = rawNode.cloneNode(true);
-    rawNode.parentNode.insertBefore(clonedNode, rawNode.nextSibling);
-  },
-
-  /**
-   * Test whether a node is a document or a document element.
-   *
-   * @param {NodeActor} node The node to remove.
-   * @return {boolean} True if the node is a document or a document element.
-   */
-  isDocumentOrDocumentElementNode: function (node) {
-    return ((node.rawNode.ownerDocument &&
-      node.rawNode.ownerDocument.documentElement === this.rawNode) ||
-      node.rawNode.nodeType === Ci.nsIDOMNode.DOCUMENT_NODE);
-  },
-
-  /**
-   * Removes a node from its parent node.
-   *
-   * @param {NodeActor} node The node to remove.
-   * @returns The node's nextSibling before it was removed.
-   */
-  removeNode: function (node) {
-    if (isNodeDead(node) || this.isDocumentOrDocumentElementNode(node)) {
-      throw Error("Cannot remove document, document elements or dead nodes.");
-    }
-
-    let nextSibling = this.nextSibling(node);
-    node.rawNode.remove();
-    // Mutation events will take care of the rest.
-    return nextSibling;
-  },
-
-  /**
-   * Removes an array of nodes from their parent node.
-   *
-   * @param {NodeActor[]} nodes The nodes to remove.
-   */
-  removeNodes: function (nodes) {
-    // Check that all nodes are valid before processing the removals.
-    for (let node of nodes) {
-      if (isNodeDead(node) || this.isDocumentOrDocumentElementNode(node)) {
-        throw Error("Cannot remove document, document elements or dead nodes");
-      }
-    }
-
-    for (let node of nodes) {
-      node.rawNode.remove();
-      // Mutation events will take care of the rest.
-    }
-  },
-
-  /**
-   * Insert a node into the DOM.
-   */
-  insertBefore: function (node, parent, sibling) {
-    if (isNodeDead(node) ||
-        isNodeDead(parent) ||
-        (sibling && isNodeDead(sibling))) {
-      return;
-    }
-
-    let rawNode = node.rawNode;
-    let rawParent = parent.rawNode;
-    let rawSibling = sibling ? sibling.rawNode : null;
-
-    // Don't bother inserting a node if the document position isn't going
-    // to change. This prevents needless iframes reloading and mutations.
-    if (rawNode.parentNode === rawParent) {
-      let currentNextSibling = this.nextSibling(node);
-      currentNextSibling = currentNextSibling ? currentNextSibling.rawNode :
-                                                null;
-
-      if (rawNode === rawSibling || currentNextSibling === rawSibling) {
-        return;
-      }
-    }
-
-    rawParent.insertBefore(rawNode, rawSibling);
-  },
-
-  /**
-   * Editing a node's tagname actually means creating a new node with the same
-   * attributes, removing the node and inserting the new one instead.
-   * This method does not return anything as mutation events are taking care of
-   * informing the consumers about changes.
-   */
-  editTagName: function (node, tagName) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let oldNode = node.rawNode;
-
-    // Create a new element with the same attributes as the current element and
-    // prepare to replace the current node with it.
-    let newNode;
-    try {
-      newNode = nodeDocument(oldNode).createElement(tagName);
-    } catch (x) {
-      // Failed to create a new element with that tag name, ignore the change,
-      // and signal the error to the front.
-      return Promise.reject(new Error("Could not change node's tagName to " + tagName));
-    }
-
-    let attrs = oldNode.attributes;
-    for (let i = 0; i < attrs.length; i++) {
-      newNode.setAttribute(attrs[i].name, attrs[i].value);
-    }
-
-    // Insert the new node, and transfer the old node's children.
-    oldNode.parentNode.insertBefore(newNode, oldNode);
-    while (oldNode.firstChild) {
-      newNode.appendChild(oldNode.firstChild);
-    }
-
-    oldNode.remove();
-    return null;
-  },
-
-  /**
-   * Get any pending mutation records.  Must be called by the client after
-   * the `new-mutations` notification is received.  Returns an array of
-   * mutation records.
-   *
-   * Mutation records have a basic structure:
-   *
-   * {
-   *   type: attributes|characterData|childList,
-   *   target: <domnode actor ID>,
-   * }
-   *
-   * And additional attributes based on the mutation type:
-   *
-   * `attributes` type:
-   *   attributeName: <string> - the attribute that changed
-   *   attributeNamespace: <string> - the attribute's namespace URI, if any.
-   *   newValue: <string> - The new value of the attribute, if any.
-   *
-   * `characterData` type:
-   *   newValue: <string> - the new nodeValue for the node
-   *
-   * `childList` type is returned when the set of children for a node
-   * has changed.  Includes extra data, which can be used by the client to
-   * maintain its ownership subtree.
-   *
-   *   added: array of <domnode actor ID> - The list of actors *previously
-   *     seen by the client* that were added to the target node.
-   *   removed: array of <domnode actor ID> The list of actors *previously
-   *     seen by the client* that were removed from the target node.
-   *   inlineTextChild: If the node now has a single text child, it will
-   *     be sent here.
-   *
-   * Actors that are included in a MutationRecord's `removed` but
-   * not in an `added` have been removed from the client's ownership
-   * tree (either by being moved under a node the client has seen yet
-   * or by being removed from the tree entirely), and is considered
-   * 'orphaned'.
-   *
-   * Keep in mind that if a node that the client hasn't seen is moved
-   * into or out of the target node, it will not be included in the
-   * removedNodes and addedNodes list, so if the client is interested
-   * in the new set of children it needs to issue a `children` request.
-   */
-  getMutations: function (options = {}) {
-    let pending = this._pendingMutations || [];
-    this._pendingMutations = [];
-    this._waitingForGetMutations = false;
-
-    if (options.cleanup) {
-      for (let node of this._orphaned) {
-        // Release the orphaned node.  Nodes or children that have been
-        // retained will be moved to this._retainedOrphans.
-        this.releaseNode(node);
-      }
-      this._orphaned = new Set();
-    }
-
-    return pending;
-  },
-
-  queueMutation: function (mutation) {
-    if (!this.actorID || this._destroyed) {
-      // We've been destroyed, don't bother queueing this mutation.
-      return;
-    }
-
-    // Add the mutation to the list of mutations to be retrieved next.
-    this._pendingMutations.push(mutation);
-
-    // Bail out if we already emitted a new-mutations event and are waiting for a client
-    // to retrieve them.
-    if (this._waitingForGetMutations) {
-      return;
-    }
-
-    if (IMMEDIATE_MUTATIONS.includes(mutation.type)) {
-      this._emitNewMutations();
-    } else {
-      /**
-       * If many mutations are fired at the same time, clients might sequentially request
-       * children/siblings for updated nodes, which can be costly. By throttling the calls
-       * to getMutations, duplicated mutations will be ignored.
-       */
-      this._throttledEmitNewMutations();
-    }
-  },
-
-  _emitNewMutations: function () {
-    if (!this.actorID || this._destroyed) {
-      // Bail out if the actor was destroyed after throttling this call.
-      return;
-    }
-
-    if (this._waitingForGetMutations || this._pendingMutations.length == 0) {
-      // Bail out if we already fired the new-mutation event or if no mutations are
-      // waiting to be retrieved.
-      return;
-    }
-
-    this._waitingForGetMutations = true;
-    this.emit("new-mutations");
-  },
-
-  /**
-   * Handles mutations from the DOM mutation observer API.
-   *
-   * @param array[MutationRecord] mutations
-   *    See https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver#MutationRecord
-   */
-  onMutations: function (mutations) {
-    // Notify any observers that want *all* mutations (even on nodes that aren't
-    // referenced).  This is not sent over the protocol so can only be used by
-    // scripts running in the server process.
-    this.emit("any-mutation");
-
-    for (let change of mutations) {
-      let targetActor = this.getNode(change.target);
-      if (!targetActor) {
-        continue;
-      }
-      let targetNode = change.target;
-      let type = change.type;
-      let mutation = {
-        type: type,
-        target: targetActor.actorID,
-      };
-
-      if (type === "attributes") {
-        mutation.attributeName = change.attributeName;
-        mutation.attributeNamespace = change.attributeNamespace || undefined;
-        mutation.newValue = targetNode.hasAttribute(mutation.attributeName) ?
-                            targetNode.getAttribute(mutation.attributeName)
-                            : null;
-      } else if (type === "characterData") {
-        mutation.newValue = targetNode.nodeValue;
-        this._maybeQueueInlineTextChildMutation(change, targetNode);
-      } else if (type === "childList" || type === "nativeAnonymousChildList") {
-        // Get the list of removed and added actors that the client has seen
-        // so that it can keep its ownership tree up to date.
-        let removedActors = [];
-        let addedActors = [];
-        for (let removed of change.removedNodes) {
-          let removedActor = this.getNode(removed);
-          if (!removedActor) {
-            // If the client never encountered this actor we don't need to
-            // mention that it was removed.
-            continue;
-          }
-          // While removed from the tree, nodes are saved as orphaned.
-          this._orphaned.add(removedActor);
-          removedActors.push(removedActor.actorID);
-        }
-        for (let added of change.addedNodes) {
-          let addedActor = this.getNode(added);
-          if (!addedActor) {
-            // If the client never encounted this actor we don't need to tell
-            // it about its addition for ownership tree purposes - if the
-            // client wants to see the new nodes it can ask for children.
-            continue;
-          }
-          // The actor is reconnected to the ownership tree, unorphan
-          // it and let the client know so that its ownership tree is up
-          // to date.
-          this._orphaned.delete(addedActor);
-          addedActors.push(addedActor.actorID);
-        }
-
-        mutation.numChildren = targetActor.numChildren;
-        mutation.removed = removedActors;
-        mutation.added = addedActors;
-
-        let inlineTextChild = this.inlineTextChild(targetActor);
-        if (inlineTextChild) {
-          mutation.inlineTextChild = inlineTextChild.form();
-        }
-      }
-      this.queueMutation(mutation);
-    }
-  },
-
-  /**
-   * Check if the provided mutation could change the way the target element is
-   * inlined with its parent node. If it might, a custom mutation of type
-   * "inlineTextChild" will be queued.
-   *
-   * @param {MutationRecord} mutation
-   *        A characterData type mutation
-   */
-  _maybeQueueInlineTextChildMutation: function (mutation) {
-    let {oldValue, target} = mutation;
-    let newValue = target.nodeValue;
-    let limit = gValueSummaryLength;
-
-    if ((oldValue.length <= limit && newValue.length <= limit) ||
-        (oldValue.length > limit && newValue.length > limit)) {
-      // Bail out if the new & old values are both below/above the size limit.
-      return;
-    }
-
-    let parentActor = this.getNode(target.parentNode);
-    if (!parentActor || parentActor.rawNode.children.length > 0) {
-      // If the parent node has other children, a character data mutation will
-      // not change anything regarding inlining text nodes.
-      return;
-    }
-
-    let inlineTextChild = this.inlineTextChild(parentActor);
-    this.queueMutation({
-      type: "inlineTextChild",
-      target: parentActor.actorID,
-      inlineTextChild:
-        inlineTextChild ? inlineTextChild.form() : undefined
-    });
-  },
-
-  onFrameLoad: function ({ window, isTopLevel }) {
-    let { readyState } = window.document;
-    if (readyState != "interactive" && readyState != "complete") {
-      window.addEventListener("DOMContentLoaded",
-        this.onFrameLoad.bind(this, { window, isTopLevel }),
-        { once: true });
-      return;
-    }
-    if (isTopLevel) {
-      // If we initialize the inspector while the document is loading,
-      // we may already have a root document set in the constructor.
-      if (this.rootDoc && !Cu.isDeadWrapper(this.rootDoc) &&
-          this.rootDoc.defaultView) {
-        this.onFrameUnload({ window: this.rootDoc.defaultView });
-      }
-      // Update all DOM objects references to target the new document.
-      this.rootWin = window;
-      this.rootDoc = window.document;
-      this.rootNode = this.document();
-      this.queueMutation({
-        type: "newRoot",
-        target: this.rootNode.form()
-      });
-      return;
-    }
-    let frame = getFrameElement(window);
-    let frameActor = this.getNode(frame);
-    if (!frameActor) {
-      return;
-    }
-
-    this.queueMutation({
-      type: "frameLoad",
-      target: frameActor.actorID,
-    });
-
-    // Send a childList mutation on the frame.
-    this.queueMutation({
-      type: "childList",
-      target: frameActor.actorID,
-      added: [],
-      removed: []
-    });
-  },
-
-  // Returns true if domNode is in window or a subframe.
-  _childOfWindow: function (window, domNode) {
-    let win = nodeDocument(domNode).defaultView;
-    while (win) {
-      if (win === window) {
-        return true;
-      }
-      win = getFrameElement(win);
-    }
-    return false;
-  },
-
-  onFrameUnload: function ({ window }) {
-    // Any retained orphans that belong to this document
-    // or its children need to be released, and a mutation sent
-    // to notify of that.
-    let releasedOrphans = [];
-
-    for (let retained of this._retainedOrphans) {
-      if (Cu.isDeadWrapper(retained.rawNode) ||
-          this._childOfWindow(window, retained.rawNode)) {
-        this._retainedOrphans.delete(retained);
-        releasedOrphans.push(retained.actorID);
-        this.releaseNode(retained, { force: true });
-      }
-    }
-
-    if (releasedOrphans.length > 0) {
-      this.queueMutation({
-        target: this.rootNode.actorID,
-        type: "unretained",
-        nodes: releasedOrphans
-      });
-    }
-
-    let doc = window.document;
-    let documentActor = this.getNode(doc);
-    if (!documentActor) {
-      return;
-    }
-
-    if (this.rootDoc === doc) {
-      this.rootDoc = null;
-      this.rootNode = null;
-    }
-
-    this.queueMutation({
-      type: "documentUnload",
-      target: documentActor.actorID
-    });
-
-    let walker = this.getDocumentWalker(doc);
-    let parentNode = walker.parentNode();
-    if (parentNode) {
-      // Send a childList mutation on the frame so that clients know
-      // they should reread the children list.
-      this.queueMutation({
-        type: "childList",
-        target: this.getNode(parentNode).actorID,
-        added: [],
-        removed: []
-      });
-    }
-
-    // Need to force a release of this node, because those nodes can't
-    // be accessed anymore.
-    this.releaseNode(documentActor, { force: true });
-  },
-
-  /**
-   * Check if a node is attached to the DOM tree of the current page.
-   * @param {nsIDomNode} rawNode
-   * @return {Boolean} false if the node is removed from the tree or within a
-   * document fragment
-   */
-  _isInDOMTree: function (rawNode) {
-    let walker = this.getDocumentWalker(rawNode);
-    let current = walker.currentNode;
-
-    // Reaching the top of tree
-    while (walker.parentNode()) {
-      current = walker.currentNode;
-    }
-
-    // The top of the tree is a fragment or is not rootDoc, hence rawNode isn't
-    // attached
-    if (current.nodeType === Ci.nsIDOMNode.DOCUMENT_FRAGMENT_NODE ||
-        current !== this.rootDoc) {
-      return false;
-    }
-
-    // Otherwise the top of the tree is rootDoc, hence rawNode is in rootDoc
-    return true;
-  },
-
-  /**
-   * @see _isInDomTree
-   */
-  isInDOMTree: function (node) {
-    if (isNodeDead(node)) {
-      return false;
-    }
-    return this._isInDOMTree(node.rawNode);
-  },
-
-  /**
-   * Given an ObjectActor (identified by its ID), commonly used in the debugger,
-   * webconsole and variablesView, return the corresponding inspector's
-   * NodeActor
-   */
-  getNodeActorFromObjectActor: function (objectActorID) {
-    let actor = this.conn.getActor(objectActorID);
-    if (!actor) {
-      return null;
-    }
-
-    let debuggerObject = this.conn.getActor(objectActorID).obj;
-    let rawNode = debuggerObject.unsafeDereference();
-
-    if (!this._isInDOMTree(rawNode)) {
-      return null;
-    }
-
-    // This is a special case for the document object whereby it is considered
-    // as document.documentElement (the <html> node)
-    if (rawNode.defaultView && rawNode === rawNode.defaultView.document) {
-      rawNode = rawNode.documentElement;
-    }
-
-    return this.attachElement(rawNode);
-  },
-
-  /**
-   * Given a windowID return the NodeActor for the corresponding frameElement,
-   * unless it's the root window
-   */
-  getNodeActorFromWindowID: function (windowID) {
-    let win;
-
-    try {
-      win = Services.wm.getOuterWindowWithId(windowID);
-    } catch (e) {
-      // ignore
-    }
-
-    if (!win) {
-      return { error: "noWindow",
-               message: "The related docshell is destroyed or not found" };
-    } else if (!win.frameElement) {
-      // the frame element of the root document is privileged & thus
-      // inaccessible, so return the document body/element instead
-      return this.attachElement(win.document.body || win.document.documentElement);
-    }
-
-    return this.attachElement(win.frameElement);
-  },
-
-  /**
-   * Given a StyleSheetActor (identified by its ID), commonly used in the
-   * style-editor, get its ownerNode and return the corresponding walker's
-   * NodeActor.
-   * Note that getNodeFromActor was added later and can now be used instead.
-   */
-  getStyleSheetOwnerNode: function (styleSheetActorID) {
-    return this.getNodeFromActor(styleSheetActorID, ["ownerNode"]);
-  },
-
-  /**
-   * This method can be used to retrieve NodeActor for DOM nodes from other
-   * actors in a way that they can later be highlighted in the page, or
-   * selected in the inspector.
-   * If an actor has a reference to a DOM node, and the UI needs to know about
-   * this DOM node (and possibly select it in the inspector), the UI should
-   * first retrieve a reference to the walkerFront:
-   *
-   * // Make sure the inspector/walker have been initialized first.
-   * toolbox.initInspector().then(() => {
-   *  // Retrieve the walker.
-   *  let walker = toolbox.walker;
-   * });
-   *
-   * And then call this method:
-   *
-   * // Get the nodeFront from my actor, passing the ID and properties path.
-   * walker.getNodeFromActor(myActorID, ["element"]).then(nodeFront => {
-   *   // Use the nodeFront, e.g. select the node in the inspector.
-   *   toolbox.getPanel("inspector").selection.setNodeFront(nodeFront);
-   * });
-   *
-   * @param {String} actorID The ID for the actor that has a reference to the
-   * DOM node.
-   * @param {Array} path Where, on the actor, is the DOM node stored. If in the
-   * scope of the actor, the node is available as `this.data.node`, then this
-   * should be ["data", "node"].
-   * @return {NodeActor} The attached NodeActor, or null if it couldn't be
-   * found.
-   */
-  getNodeFromActor: function (actorID, path) {
-    let actor = this.conn.getActor(actorID);
-    if (!actor) {
-      return null;
-    }
-
-    let obj = actor;
-    for (let name of path) {
-      if (!(name in obj)) {
-        return null;
-      }
-      obj = obj[name];
-    }
-
-    return this.attachElement(obj);
-  },
-
-  /**
-   * Returns an instance of the LayoutActor that is used to retrieve CSS layout-related
-   * information.
-   *
-   * @return {LayoutActor}
-   */
-  getLayoutInspector: function () {
-    if (!this.layoutActor) {
-      this.layoutActor = new LayoutActor(this.conn, this.tabActor, this);
-    }
-
-    return this.layoutActor;
-  },
-
-  /**
-   * Returns the offset parent DOMNode of the given node if it exists, otherwise, it
-   * returns null.
-   */
-  getOffsetParent: function (node) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let offsetParent = node.rawNode.offsetParent;
-
-    if (!offsetParent) {
-      return null;
-    }
-
-    return this._ref(offsetParent);
-  },
-});
-
-/**
- * Server side of the inspector actor, which is used to create
- * inspector-related actors, including the walker.
- */
-exports.InspectorActor = protocol.ActorClassWithSpec(inspectorSpec, {
-  initialize: function (conn, tabActor) {
-    protocol.Actor.prototype.initialize.call(this, conn);
-    this.tabActor = tabActor;
-
-    this._onColorPicked = this._onColorPicked.bind(this);
-    this._onColorPickCanceled = this._onColorPickCanceled.bind(this);
-    this.destroyEyeDropper = this.destroyEyeDropper.bind(this);
-  },
-
-  destroy: function () {
-    protocol.Actor.prototype.destroy.call(this);
-
-    this.destroyEyeDropper();
-
-    this._highlighterPromise = null;
-    this._pageStylePromise = null;
-    this._walkerPromise = null;
-    this.walker = null;
-    this.tabActor = null;
-  },
-
-  get window() {
-    return this.tabActor.window;
-  },
-
-  getWalker: function (options = {}) {
-    if (this._walkerPromise) {
-      return this._walkerPromise;
-    }
-
-    let deferred = defer();
-    this._walkerPromise = deferred.promise;
-
-    let window = this.window;
-    let domReady = () => {
-      let tabActor = this.tabActor;
-      window.removeEventListener("DOMContentLoaded", domReady, true);
-      this.walker = WalkerActor(this.conn, tabActor, options);
-      this.manage(this.walker);
-      this.walker.once("destroyed", () => {
-        this._walkerPromise = null;
-        this._pageStylePromise = null;
-      });
-      deferred.resolve(this.walker);
-    };
-
-    if (window.document.readyState === "loading") {
-      window.addEventListener("DOMContentLoaded", domReady, true);
-    } else {
-      domReady();
-    }
-
-    return this._walkerPromise;
-  },
-
-  getPageStyle: function () {
-    if (this._pageStylePromise) {
-      return this._pageStylePromise;
-    }
-
-    this._pageStylePromise = this.getWalker().then(walker => {
-      let pageStyle = PageStyleActor(this);
-      this.manage(pageStyle);
-      return pageStyle;
-    });
-    return this._pageStylePromise;
-  },
-
-  /**
-   * The most used highlighter actor is the HighlighterActor which can be
-   * conveniently retrieved by this method.
-   * The same instance will always be returned by this method when called
-   * several times.
-   * The highlighter actor returned here is used to highlighter elements's
-   * box-models from the markup-view, box model, console, debugger, ... as
-   * well as select elements with the pointer (pick).
-   *
-   * @param {Boolean} autohide Optionally autohide the highlighter after an
-   * element has been picked
-   * @return {HighlighterActor}
-   */
-  getHighlighter: function (autohide) {
-    if (this._highlighterPromise) {
-      return this._highlighterPromise;
-    }
-
-    this._highlighterPromise = this.getWalker().then(walker => {
-      let highlighter = HighlighterActor(this, autohide);
-      this.manage(highlighter);
-      return highlighter;
-    });
-    return this._highlighterPromise;
-  },
-
-  /**
-   * If consumers need to display several highlighters at the same time or
-   * different types of highlighters, then this method should be used, passing
-   * the type name of the highlighter needed as argument.
-   * A new instance will be created everytime the method is called, so it's up
-   * to the consumer to release it when it is not needed anymore
-   *
-   * @param {String} type The type of highlighter to create
-   * @return {Highlighter} The highlighter actor instance or null if the
-   * typeName passed doesn't match any available highlighter
-   */
-  getHighlighterByType: function (typeName) {
-    if (isTypeRegistered(typeName)) {
-      return CustomHighlighterActor(this, typeName);
-    }
-    return null;
-  },
-
-  /**
-   * Get the node's image data if any (for canvas and img nodes).
-   * Returns an imageData object with the actual data being a LongStringActor
-   * and a size json object.
-   * The image data is transmitted as a base64 encoded png data-uri.
-   * The method rejects if the node isn't an image or if the image is missing
-   *
-   * Accepts a maxDim request parameter to resize images that are larger. This
-   * is important as the resizing occurs server-side so that image-data being
-   * transfered in the longstring back to the client will be that much smaller
-   */
-  getImageDataFromURL: function (url, maxDim) {
-    let img = new this.window.Image();
-    img.src = url;
-
-    // imageToImageData waits for the image to load.
-    return imageToImageData(img, maxDim).then(imageData => {
-      return {
-        data: LongStringActor(this.conn, imageData.data),
-        size: imageData.size
-      };
-    });
-  },
-
-  /**
-   * Resolve a URL to its absolute form, in the scope of a given content window.
-   * @param {String} url.
-   * @param {NodeActor} node If provided, the owner window of this node will be
-   * used to resolve the URL. Otherwise, the top-level content window will be
-   * used instead.
-   * @return {String} url.
-   */
-  resolveRelativeURL: function (url, node) {
-    let document = isNodeDead(node)
-                   ? this.window.document
-                   : nodeDocument(node.rawNode);
-
-    if (!document) {
-      return url;
-    }
-
-    let baseURI = Services.io.newURI(document.location.href);
-    return Services.io.newURI(url, null, baseURI).spec;
-  },
-
-  /**
-   * Create an instance of the eye-dropper highlighter and store it on this._eyeDropper.
-   * Note that for now, a new instance is created every time to deal with page navigation.
-   */
-  createEyeDropper: function () {
-    this.destroyEyeDropper();
-    this._highlighterEnv = new HighlighterEnvironment();
-    this._highlighterEnv.initFromTabActor(this.tabActor);
-    this._eyeDropper = new EyeDropper(this._highlighterEnv);
-  },
-
-  /**
-   * Destroy the current eye-dropper highlighter instance.
-   */
-  destroyEyeDropper: function () {
-    if (this._eyeDropper) {
-      this.cancelPickColorFromPage();
-      this._eyeDropper.destroy();
-      this._eyeDropper = null;
-      this._highlighterEnv.destroy();
-      this._highlighterEnv = null;
-    }
-  },
-
-  /**
-   * Pick a color from the page using the eye-dropper. This method doesn't return anything
-   * but will cause events to be sent to the front when a color is picked or when the user
-   * cancels the picker.
-   * @param {Object} options
-   */
-  pickColorFromPage: function (options) {
-    this.createEyeDropper();
-    this._eyeDropper.show(this.window.document.documentElement, options);
-    this._eyeDropper.once("selected", this._onColorPicked);
-    this._eyeDropper.once("canceled", this._onColorPickCanceled);
-    this.tabActor.once("will-navigate", this.destroyEyeDropper);
-  },
-
-  /**
-   * After the pickColorFromPage method is called, the only way to dismiss the eye-dropper
-   * highlighter is for the user to click in the page and select a color. If you need to
-   * dismiss the eye-dropper programatically instead, use this method.
-   */
-  cancelPickColorFromPage: function () {
-    if (this._eyeDropper) {
-      this._eyeDropper.hide();
-      this._eyeDropper.off("selected", this._onColorPicked);
-      this._eyeDropper.off("canceled", this._onColorPickCanceled);
-      this.tabActor.off("will-navigate", this.destroyEyeDropper);
-    }
-  },
-
-  /**
-   * Check if the current document supports highlighters using a canvasFrame anonymous
-   * content container (ie all highlighters except the SimpleOutlineHighlighter).
-   * It is impossible to detect the feature programmatically as some document types simply
-   * don't render the canvasFrame without throwing any error.
-   */
-  supportsHighlighters: function () {
-    let doc = this.tabActor.window.document;
-    let ns = doc.documentElement.namespaceURI;
-
-    // XUL documents do not support insertAnonymousContent().
-    if (ns === XUL_NS) {
-      return false;
-    }
-
-    // SVG documents do not render the canvasFrame (see Bug 1157592).
-    if (ns === SVG_NS) {
-      return false;
-    }
-
-    return true;
-  },
-
-  _onColorPicked: function (e, color) {
-    this.emit("color-picked", color);
-  },
-
-  _onColorPickCanceled: function () {
-    this.emit("color-pick-canceled");
-  }
-});
-
-// Exported for test purposes.
-exports._documentWalker = DocumentWalker;
-
-function nodeDocument(node) {
-  if (Cu.isDeadWrapper(node)) {
-    return null;
-  }
-  return node.ownerDocument ||
-         (node.nodeType == Ci.nsIDOMNode.DOCUMENT_NODE ? node : null);
-}
-
-function nodeDocshell(node) {
-  let doc = node ? nodeDocument(node) : null;
-  let win = doc ? doc.defaultView : null;
-  if (win) {
-    return win.QueryInterface(Ci.nsIInterfaceRequestor)
-              .getInterface(Ci.nsIDocShell);
-  }
-  return null;
-}
-
-function isNodeDead(node) {
-  return !node || !node.rawNode || Cu.isDeadWrapper(node.rawNode);
-}
-
 /**
  * Wrapper for inDeepTreeWalker.  Adds filtering to the traversal methods.
  * See inDeepTreeWalker for more information about the methods.
  *
  * @param {DOMNode} node
  * @param {Window} rootWin
  * @param {Number} whatToShow
  *        See nodeFilterConstants / inIDeepTreeWalker for options.
@@ -3057,19 +26,19 @@ function isNodeDead(node) {
  *        A custom filter function Taking in a DOMNode and returning an Int. See
  *        WalkerActor.nodeFilter for an example.
  * @param {String} skipTo
  *        Either SKIP_TO_PARENT or SKIP_TO_SIBLING. If the provided node is not compatible
  *        with the filter function for this walker, try to find a compatible one either
  *        in the parents or in the siblings of the node.
  */
 function DocumentWalker(node, rootWin,
-    whatToShow = nodeFilterConstants.SHOW_ALL,
-    filter = standardTreeWalkerFilter,
-    skipTo = SKIP_TO_PARENT) {
+  whatToShow = nodeFilterConstants.SHOW_ALL,
+  filter = standardTreeWalkerFilter,
+  skipTo = SKIP_TO_PARENT) {
   if (Cu.isDeadWrapper(rootWin) || !rootWin.location) {
     throw new Error("Got an invalid root window in DocumentWalker");
   }
 
   this.walker = Cc["@mozilla.org/inspector/deep-tree-walker;1"]
     .createInstance(Ci.inIDeepTreeWalker);
   this.walker.showAnonymousContent = true;
   this.walker.showSubDocuments = true;
@@ -3078,16 +47,17 @@ function DocumentWalker(node, rootWin,
   this.filter = filter;
 
   // Make sure that the walker knows about the initial node (which could
   // be skipped due to a filter).
   this.walker.currentNode = this.getStartingNode(node, skipTo);
 }
 
 DocumentWalker.prototype = {
+
   get whatToShow() {
     return this.walker.whatToShow;
   },
   get currentNode() {
     return this.walker.currentNode;
   },
   set currentNode(val) {
     this.walker.currentNode = val;
@@ -3202,201 +172,11 @@ DocumentWalker.prototype = {
     return null;
   },
 
   isSkippedNode: function (node) {
     return this.filter(node) === nodeFilterConstants.FILTER_SKIP;
   },
 };
 
-function isInXULDocument(el) {
-  let doc = nodeDocument(el);
-  return doc &&
-         doc.documentElement &&
-         doc.documentElement.namespaceURI === XUL_NS;
-}
-
-/**
- * This DeepTreeWalker filter skips whitespace text nodes and anonymous
- * content with the exception of ::before and ::after and anonymous content
- * in XUL document (needed to show all elements in the browser toolbox).
- */
-function standardTreeWalkerFilter(node) {
-  // ::before and ::after are native anonymous content, but we always
-  // want to show them
-  if (node.nodeName === "_moz_generated_content_before" ||
-      node.nodeName === "_moz_generated_content_after") {
-    return nodeFilterConstants.FILTER_ACCEPT;
-  }
-
-  // Ignore empty whitespace text nodes that do not impact the layout.
-  if (isWhitespaceTextNode(node)) {
-    return nodeHasSize(node)
-           ? nodeFilterConstants.FILTER_ACCEPT
-           : nodeFilterConstants.FILTER_SKIP;
-  }
-
-  // Ignore all native and XBL anonymous content inside a non-XUL document.
-  // We need to do this to skip things like form controls, scrollbars,
-  // video controls, etc (see bug 1187482).
-  if (!isInXULDocument(node) && (isXBLAnonymous(node) ||
-                                  isNativeAnonymous(node))) {
-    return nodeFilterConstants.FILTER_SKIP;
-  }
-
-  return nodeFilterConstants.FILTER_ACCEPT;
-}
-
-/**
- * This DeepTreeWalker filter is like standardTreeWalkerFilter except that
- * it also includes all anonymous content (like internal form controls).
- */
-function allAnonymousContentTreeWalkerFilter(node) {
-  // Ignore empty whitespace text nodes that do not impact the layout.
-  if (isWhitespaceTextNode(node)) {
-    return nodeHasSize(node)
-           ? nodeFilterConstants.FILTER_ACCEPT
-           : nodeFilterConstants.FILTER_SKIP;
-  }
-  return nodeFilterConstants.FILTER_ACCEPT;
-}
-
-/**
- * Is the given node a text node composed of whitespace only?
- * @param {DOMNode} node
- * @return {Boolean}
- */
-function isWhitespaceTextNode(node) {
-  return node.nodeType == Ci.nsIDOMNode.TEXT_NODE && !/[^\s]/.exec(node.nodeValue);
-}
-
-/**
- * Does the given node have non-0 width and height?
- * @param {DOMNode} node
- * @return {Boolean}
- */
-function nodeHasSize(node) {
-  if (!node.getBoxQuads) {
-    return false;
-  }
-
-  let quads = node.getBoxQuads();
-  return quads.length && quads.some(quad => quad.bounds.width && quad.bounds.height);
-}
-
-/**
- * Returns a promise that is settled once the given HTMLImageElement has
- * finished loading.
- *
- * @param {HTMLImageElement} image - The image element.
- * @param {Number} timeout - Maximum amount of time the image is allowed to load
- * before the waiting is aborted. Ignored if flags.testing is set.
- *
- * @return {Promise} that is fulfilled once the image has loaded. If the image
- * fails to load or the load takes too long, the promise is rejected.
- */
-function ensureImageLoaded(image, timeout) {
-  let { HTMLImageElement } = image.ownerGlobal;
-  if (!(image instanceof HTMLImageElement)) {
-    return promise.reject("image must be an HTMLImageELement");
-  }
-
-  if (image.complete) {
-    // The image has already finished loading.
-    return promise.resolve();
-  }
-
-  // This image is still loading.
-  let onLoad = AsyncUtils.listenOnce(image, "load");
-
-  // Reject if loading fails.
-  let onError = AsyncUtils.listenOnce(image, "error").then(() => {
-    return promise.reject("Image '" + image.src + "' failed to load.");
-  });
-
-  // Don't timeout when testing. This is never settled.
-  let onAbort = new Promise(() => {});
-
-  if (!flags.testing) {
-    // Tests are not running. Reject the promise after given timeout.
-    onAbort = DevToolsUtils.waitForTime(timeout).then(() => {
-      return promise.reject("Image '" + image.src + "' took too long to load.");
-    });
-  }
-
-  // See which happens first.
-  return promise.race([onLoad, onError, onAbort]);
-}
-
-/**
- * Given an <img> or <canvas> element, return the image data-uri. If @param node
- * is an <img> element, the method waits a while for the image to load before
- * the data is generated. If the image does not finish loading in a reasonable
- * time (IMAGE_FETCHING_TIMEOUT milliseconds) the process aborts.
- *
- * @param {HTMLImageElement|HTMLCanvasElement} node - The <img> or <canvas>
- * element, or Image() object. Other types cause the method to reject.
- * @param {Number} maxDim - Optionally pass a maximum size you want the longest
- * side of the image to be resized to before getting the image data.
-
- * @return {Promise} A promise that is fulfilled with an object containing the
- * data-uri and size-related information:
- * { data: "...",
- *   size: {
- *     naturalWidth: 400,
- *     naturalHeight: 300,
- *     resized: true }
- *  }.
- *
- * If something goes wrong, the promise is rejected.
- */
-var imageToImageData = Task.async(function* (node, maxDim) {
-  let { HTMLCanvasElement, HTMLImageElement } = node.ownerGlobal;
-
-  let isImg = node instanceof HTMLImageElement;
-  let isCanvas = node instanceof HTMLCanvasElement;
-
-  if (!isImg && !isCanvas) {
-    throw new Error("node is not a <canvas> or <img> element.");
-  }
-
-  if (isImg) {
-    // Ensure that the image is ready.
-    yield ensureImageLoaded(node, IMAGE_FETCHING_TIMEOUT);
-  }
-
-  // Get the image resize ratio if a maxDim was provided
-  let resizeRatio = 1;
-  let imgWidth = node.naturalWidth || node.width;
-  let imgHeight = node.naturalHeight || node.height;
-  let imgMax = Math.max(imgWidth, imgHeight);
-  if (maxDim && imgMax > maxDim) {
-    resizeRatio = maxDim / imgMax;
-  }
-
-  // Extract the image data
-  let imageData;
-  // The image may already be a data-uri, in which case, save ourselves the
-  // trouble of converting via the canvas.drawImage.toDataURL method, but only
-  // if the image doesn't need resizing
-  if (isImg && node.src.startsWith("data:") && resizeRatio === 1) {
-    imageData = node.src;
-  } else {
-    // Create a canvas to copy the rawNode into and get the imageData from
-    let canvas = node.ownerDocument.createElementNS(XHTML_NS, "canvas");
-    canvas.width = imgWidth * resizeRatio;
-    canvas.height = imgHeight * resizeRatio;
-    let ctx = canvas.getContext("2d");
-
-    // Copy the rawNode image or canvas in the new canvas and extract data
-    ctx.drawImage(node, 0, 0, canvas.width, canvas.height);
-    imageData = canvas.toDataURL("image/png");
-  }
-
-  return {
-    data: imageData,
-    size: {
-      naturalWidth: imgWidth,
-      naturalHeight: imgHeight,
-      resized: resizeRatio !== 1
-    }
-  };
-});
+exports.DocumentWalker = DocumentWalker;
+exports.SKIP_TO_PARENT = SKIP_TO_PARENT;
+exports.SKIP_TO_SIBLING = SKIP_TO_SIBLING;
--- a/devtools/server/actors/inspector/inspector.js
+++ b/devtools/server/actors/inspector/inspector.js
@@ -45,2739 +45,34 @@
  * the client - when a node is disconnected from the DOM tree we want to be
  * able to free the client objects for all the children nodes.
  *
  * So to be able to answer "all the children of a given node that we have
  * seen on the client side", we guarantee that every time we've seen a node,
  * we connect it up through its parents.
  */
 
-const {Cc, Ci, Cu} = require("chrome");
 const Services = require("Services");
 const protocol = require("devtools/shared/protocol");
 const {LongStringActor} = require("devtools/server/actors/string");
-const promise = require("promise");
 const defer = require("devtools/shared/defer");
-const {Task} = require("devtools/shared/task");
-const EventEmitter = require("devtools/shared/event-emitter");
-const InspectorUtils = require("InspectorUtils");
 
-const {walkerSpec, inspectorSpec} = require("devtools/shared/specs/inspector");
-const {nodeSpec, nodeListSpec} = require("devtools/shared/specs/node");
+const {inspectorSpec} = require("devtools/shared/specs/inspector");
 
-loader.lazyRequireGetter(this, "DevToolsUtils", "devtools/shared/DevToolsUtils");
-loader.lazyRequireGetter(this, "AsyncUtils", "devtools/shared/async-utils");
-loader.lazyRequireGetter(this, "CssLogic", "devtools/server/css-logic", true);
-loader.lazyRequireGetter(this, "findCssSelector", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "getCssPath", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "getXPath", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "colorUtils", "devtools/shared/css/color", true);
+loader.lazyRequireGetter(this, "InspectorActorUtils", "devtools/server/actors/inspector/utils");
+loader.lazyRequireGetter(this, "WalkerActor", "devtools/server/actors/inspector/walker-actor", true);
 loader.lazyRequireGetter(this, "EyeDropper", "devtools/server/actors/highlighters/eye-dropper", true);
-loader.lazyRequireGetter(this, "WalkerSearch", "devtools/server/actors/utils/walker-search", true);
 loader.lazyRequireGetter(this, "PageStyleActor", "devtools/server/actors/styles", true);
-loader.lazyRequireGetter(this, "getFontPreviewData", "devtools/server/actors/styles", true);
-loader.lazyRequireGetter(this, "flags", "devtools/shared/flags");
-loader.lazyRequireGetter(this, "throttle", "devtools/shared/throttle", true);
-loader.lazyRequireGetter(this, "LayoutActor", "devtools/server/actors/layout", true);
 loader.lazyRequireGetter(this, "HighlighterActor", "devtools/server/actors/highlighters", true);
 loader.lazyRequireGetter(this, "CustomHighlighterActor", "devtools/server/actors/highlighters", true);
 loader.lazyRequireGetter(this, "isTypeRegistered", "devtools/server/actors/highlighters", true);
 loader.lazyRequireGetter(this, "HighlighterEnvironment", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "EventParsers", "devtools/server/event-parsers", true);
-loader.lazyRequireGetter(this, "isAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "isNativeAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "isXBLAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "isShadowAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "getFrameElement", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "loadSheet", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "getLayoutChangesObserver", "devtools/server/actors/reflow", true);
-loader.lazyRequireGetter(this, "releaseLayoutChangesObserver", "devtools/server/actors/reflow", true);
-loader.lazyRequireGetter(this, "nodeFilterConstants", "devtools/shared/dom-node-filter-constants");
 
-loader.lazyServiceGetter(this, "DOMParser",
-  "@mozilla.org/xmlextras/domparser;1", "nsIDOMParser");
-
-loader.lazyServiceGetter(this, "eventListenerService",
-  "@mozilla.org/eventlistenerservice;1", "nsIEventListenerService");
-
-const FONT_FAMILY_PREVIEW_TEXT = "The quick brown fox jumps over the lazy dog";
-const FONT_FAMILY_PREVIEW_TEXT_SIZE = 20;
-const PSEUDO_CLASSES = [":hover", ":active", ":focus"];
-const HIDDEN_CLASS = "__fx-devtools-hide-shortcut__";
 const SVG_NS = "http://www.w3.org/2000/svg";
-const XHTML_NS = "http://www.w3.org/1999/xhtml";
 const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
-const IMAGE_FETCHING_TIMEOUT = 500;
-
-// Minimum delay between two "new-mutations" events.
-const MUTATIONS_THROTTLING_DELAY = 100;
-// List of mutation types that should -not- be throttled.
-const IMMEDIATE_MUTATIONS = [
-  "documentUnload",
-  "frameLoad",
-  "newRoot",
-  "pseudoClassLock",
-];
-
-// SKIP_TO_* arguments are used with the DocumentWalker, driving the strategy to use if
-// the starting node is incompatible with the filter function of the walker.
-const SKIP_TO_PARENT = "SKIP_TO_PARENT";
-const SKIP_TO_SIBLING = "SKIP_TO_SIBLING";
-
-// The possible completions to a ':' with added score to give certain values
-// some preference.
-const PSEUDO_SELECTORS = [
-  [":active", 1],
-  [":hover", 1],
-  [":focus", 1],
-  [":visited", 0],
-  [":link", 0],
-  [":first-letter", 0],
-  [":first-child", 2],
-  [":before", 2],
-  [":after", 2],
-  [":lang(", 0],
-  [":not(", 3],
-  [":first-of-type", 0],
-  [":last-of-type", 0],
-  [":only-of-type", 0],
-  [":only-child", 2],
-  [":nth-child(", 3],
-  [":nth-last-child(", 0],
-  [":nth-of-type(", 0],
-  [":nth-last-of-type(", 0],
-  [":last-child", 2],
-  [":root", 0],
-  [":empty", 0],
-  [":target", 0],
-  [":enabled", 0],
-  [":disabled", 0],
-  [":checked", 1],
-  ["::selection", 0]
-];
-
-var HELPER_SHEET = "data:text/css;charset=utf-8," + encodeURIComponent(`
-  .__fx-devtools-hide-shortcut__ {
-    visibility: hidden !important;
-  }
-
-  :-moz-devtools-highlighted {
-    outline: 2px dashed #F06!important;
-    outline-offset: -2px !important;
-  }
-`);
-
-/**
- * We only send nodeValue up to a certain size by default.  This stuff
- * controls that size.
- */
-exports.DEFAULT_VALUE_SUMMARY_LENGTH = 50;
-var gValueSummaryLength = exports.DEFAULT_VALUE_SUMMARY_LENGTH;
-
-exports.getValueSummaryLength = function () {
-  return gValueSummaryLength;
-};
-
-exports.setValueSummaryLength = function (val) {
-  gValueSummaryLength = val;
-};
-
-/**
- * Returns the properly cased version of the node's tag name, which can be
- * used when displaying said name in the UI.
- *
- * @param  {Node} rawNode
- *         Node for which we want the display name
- * @return {String}
- *         Properly cased version of the node tag name
- */
-const getNodeDisplayName = function (rawNode) {
-  if (rawNode.nodeName && !rawNode.localName) {
-    // The localName & prefix APIs have been moved from the Node interface to the Element
-    // interface. Use Node.nodeName as a fallback.
-    return rawNode.nodeName;
-  }
-  return (rawNode.prefix ? rawNode.prefix + ":" : "") + rawNode.localName;
-};
-exports.getNodeDisplayName = getNodeDisplayName;
-
-/**
- * Server side of the node actor.
- */
-var NodeActor = exports.NodeActor = protocol.ActorClassWithSpec(nodeSpec, {
-  initialize: function (walker, node) {
-    protocol.Actor.prototype.initialize.call(this, null);
-    this.walker = walker;
-    this.rawNode = node;
-    this._eventParsers = new EventParsers().parsers;
-
-    // Storing the original display of the node, to track changes when reflows
-    // occur
-    this.wasDisplayed = this.isDisplayed;
-  },
-
-  toString: function () {
-    return "[NodeActor " + this.actorID + " for " +
-      this.rawNode.toString() + "]";
-  },
-
-  /**
-   * Instead of storing a connection object, the NodeActor gets its connection
-   * from its associated walker.
-   */
-  get conn() {
-    return this.walker.conn;
-  },
-
-  isDocumentElement: function () {
-    return this.rawNode.ownerDocument &&
-           this.rawNode.ownerDocument.documentElement === this.rawNode;
-  },
-
-  destroy: function () {
-    protocol.Actor.prototype.destroy.call(this);
-
-    if (this.mutationObserver) {
-      if (!Cu.isDeadWrapper(this.mutationObserver)) {
-        this.mutationObserver.disconnect();
-      }
-      this.mutationObserver = null;
-    }
-    this.rawNode = null;
-    this.walker = null;
-  },
-
-  // Returns the JSON representation of this object over the wire.
-  form: function (detail) {
-    if (detail === "actorid") {
-      return this.actorID;
-    }
-
-    let parentNode = this.walker.parentNode(this);
-    let inlineTextChild = this.walker.inlineTextChild(this);
-
-    let form = {
-      actor: this.actorID,
-      baseURI: this.rawNode.baseURI,
-      parent: parentNode ? parentNode.actorID : undefined,
-      nodeType: this.rawNode.nodeType,
-      namespaceURI: this.rawNode.namespaceURI,
-      nodeName: this.rawNode.nodeName,
-      nodeValue: this.rawNode.nodeValue,
-      displayName: getNodeDisplayName(this.rawNode),
-      numChildren: this.numChildren,
-      inlineTextChild: inlineTextChild ? inlineTextChild.form() : undefined,
-
-      // doctype attributes
-      name: this.rawNode.name,
-      publicId: this.rawNode.publicId,
-      systemId: this.rawNode.systemId,
-
-      attrs: this.writeAttrs(),
-      isBeforePseudoElement: this.isBeforePseudoElement,
-      isAfterPseudoElement: this.isAfterPseudoElement,
-      isAnonymous: isAnonymous(this.rawNode),
-      isNativeAnonymous: isNativeAnonymous(this.rawNode),
-      isXBLAnonymous: isXBLAnonymous(this.rawNode),
-      isShadowAnonymous: isShadowAnonymous(this.rawNode),
-      pseudoClassLocks: this.writePseudoClassLocks(),
-
-      isDisplayed: this.isDisplayed,
-      isInHTMLDocument: this.rawNode.ownerDocument &&
-        this.rawNode.ownerDocument.contentType === "text/html",
-      hasEventListeners: this._hasEventListeners,
-    };
-
-    if (this.isDocumentElement()) {
-      form.isDocumentElement = true;
-    }
-
-    // Add an extra API for custom properties added by other
-    // modules/extensions.
-    form.setFormProperty = (name, value) => {
-      if (!form.props) {
-        form.props = {};
-      }
-      form.props[name] = value;
-    };
-
-    // Fire an event so, other modules can create its own properties
-    // that should be passed to the client (within the form.props field).
-    EventEmitter.emit(NodeActor, "form", {
-      target: this,
-      data: form
-    });
-
-    return form;
-  },
-
-  /**
-   * Watch the given document node for mutations using the DOM observer
-   * API.
-   */
-  watchDocument: function (callback) {
-    let node = this.rawNode;
-    // Create the observer on the node's actor.  The node will make sure
-    // the observer is cleaned up when the actor is released.
-    let observer = new node.defaultView.MutationObserver(callback);
-    observer.mergeAttributeRecords = true;
-    observer.observe(node, {
-      nativeAnonymousChildList: true,
-      attributes: true,
-      characterData: true,
-      characterDataOldValue: true,
-      childList: true,
-      subtree: true
-    });
-    this.mutationObserver = observer;
-  },
-
-  get isBeforePseudoElement() {
-    return this.rawNode.nodeName === "_moz_generated_content_before";
-  },
-
-  get isAfterPseudoElement() {
-    return this.rawNode.nodeName === "_moz_generated_content_after";
-  },
-
-  // Estimate the number of children that the walker will return without making
-  // a call to children() if possible.
-  get numChildren() {
-    // For pseudo elements, childNodes.length returns 1, but the walker
-    // will return 0.
-    if (this.isBeforePseudoElement || this.isAfterPseudoElement) {
-      return 0;
-    }
-
-    let rawNode = this.rawNode;
-    let numChildren = rawNode.childNodes.length;
-    let hasAnonChildren = rawNode.nodeType === Ci.nsIDOMNode.ELEMENT_NODE &&
-                          rawNode.ownerDocument.getAnonymousNodes(rawNode);
-
-    let hasContentDocument = rawNode.contentDocument;
-    let hasSVGDocument = rawNode.getSVGDocument && rawNode.getSVGDocument();
-    if (numChildren === 0 && (hasContentDocument || hasSVGDocument)) {
-      // This might be an iframe with virtual children.
-      numChildren = 1;
-    }
-
-    // Normal counting misses ::before/::after.  Also, some anonymous children
-    // may ultimately be skipped, so we have to consult with the walker.
-    if (numChildren === 0 || hasAnonChildren) {
-      numChildren = this.walker.children(this).nodes.length;
-    }
-
-    return numChildren;
-  },
-
-  get computedStyle() {
-    return CssLogic.getComputedStyle(this.rawNode);
-  },
-
-  /**
-   * Is the node's display computed style value other than "none"
-   */
-  get isDisplayed() {
-    // Consider all non-element nodes as displayed.
-    if (isNodeDead(this) ||
-        this.rawNode.nodeType !== Ci.nsIDOMNode.ELEMENT_NODE ||
-        this.isAfterPseudoElement ||
-        this.isBeforePseudoElement) {
-      return true;
-    }
-
-    let style = this.computedStyle;
-    if (!style) {
-      return true;
-    }
-
-    return style.display !== "none";
-  },
-
-  /**
-   * Are there event listeners that are listening on this node? This method
-   * uses all parsers registered via event-parsers.js.registerEventParser() to
-   * check if there are any event listeners.
-   */
-  get _hasEventListeners() {
-    let parsers = this._eventParsers;
-    for (let [, {hasListeners}] of parsers) {
-      try {
-        if (hasListeners && hasListeners(this.rawNode)) {
-          return true;
-        }
-      } catch (e) {
-        // An object attached to the node looked like a listener but wasn't...
-        // do nothing.
-      }
-    }
-    return false;
-  },
-
-  writeAttrs: function () {
-    if (!this.rawNode.attributes) {
-      return undefined;
-    }
-
-    return [...this.rawNode.attributes].map(attr => {
-      return {namespace: attr.namespace, name: attr.name, value: attr.value };
-    });
-  },
-
-  writePseudoClassLocks: function () {
-    if (this.rawNode.nodeType !== Ci.nsIDOMNode.ELEMENT_NODE) {
-      return undefined;
-    }
-    let ret = undefined;
-    for (let pseudo of PSEUDO_CLASSES) {
-      if (InspectorUtils.hasPseudoClassLock(this.rawNode, pseudo)) {
-        ret = ret || [];
-        ret.push(pseudo);
-      }
-    }
-    return ret;
-  },
-
-  /**
-   * Gets event listeners and adds their information to the events array.
-   *
-   * @param  {Node} node
-   *         Node for which we are to get listeners.
-   */
-  getEventListeners: function (node) {
-    let parsers = this._eventParsers;
-    let dbg = this.parent().tabActor.makeDebugger();
-    let listenerArray = [];
-
-    for (let [, {getListeners, normalizeListener}] of parsers) {
-      try {
-        let listeners = getListeners(node);
-
-        if (!listeners) {
-          continue;
-        }
-
-        for (let listener of listeners) {
-          if (normalizeListener) {
-            listener.normalizeListener = normalizeListener;
-          }
-
-          this.processHandlerForEvent(node, listenerArray, dbg, listener);
-        }
-      } catch (e) {
-        // An object attached to the node looked like a listener but wasn't...
-        // do nothing.
-      }
-    }
-
-    listenerArray.sort((a, b) => {
-      return a.type.localeCompare(b.type);
-    });
-
-    return listenerArray;
-  },
-
-  /**
-   * Process a handler
-   *
-   * @param  {Node} node
-   *         The node for which we want information.
-   * @param  {Array} listenerArray
-   *         listenerArray contains all event objects that we have gathered
-   *         so far.
-   * @param  {Debugger} dbg
-   *         JSDebugger instance.
-   * @param  {Object} eventInfo
-   *         See event-parsers.js.registerEventParser() for a description of the
-   *         eventInfo object.
-   *
-   * @return {Array}
-   *         An array of objects where a typical object looks like this:
-   *           {
-   *             type: "click",
-   *             handler: function() { doSomething() },
-   *             origin: "http://www.mozilla.com",
-   *             searchString: 'onclick="doSomething()"',
-   *             tags: tags,
-   *             DOM0: true,
-   *             capturing: true,
-   *             hide: {
-   *               DOM0: true
-   *             },
-   *             native: false
-   *           }
-   */
-  processHandlerForEvent: function (node, listenerArray, dbg, listener) {
-    let { handler } = listener;
-    let global = Cu.getGlobalForObject(handler);
-    let globalDO = dbg.addDebuggee(global);
-    let listenerDO = globalDO.makeDebuggeeValue(handler);
-
-    let { normalizeListener } = listener;
-
-    if (normalizeListener) {
-      listenerDO = normalizeListener(listenerDO, listener);
-    }
-
-    let { capturing } = listener;
-    let dom0 = false;
-    let functionSource = handler.toString();
-    let hide = listener.hide || {};
-    let line = 0;
-    let native = false;
-    let override = listener.override || {};
-    let tags = listener.tags || "";
-    let type = listener.type || "";
-    let url = "";
-
-    // If the listener is an object with a 'handleEvent' method, use that.
-    if (listenerDO.class === "Object" || listenerDO.class === "XULElement") {
-      let desc;
-
-      while (!desc && listenerDO) {
-        desc = listenerDO.getOwnPropertyDescriptor("handleEvent");
-        listenerDO = listenerDO.proto;
-      }
-
-      if (desc && desc.value) {
-        listenerDO = desc.value;
-      }
-    }
-
-    // If the listener is bound to a different context then we need to switch
-    // to the bound function.
-    if (listenerDO.isBoundFunction) {
-      listenerDO = listenerDO.boundTargetFunction;
-    }
-
-    let { isArrowFunction, name, script, parameterNames } = listenerDO;
-
-    if (script) {
-      let scriptSource = script.source.text;
-
-      // Scripts are provided via script tags. If it wasn't provided by a
-      // script tag it must be a DOM0 event.
-      if (script.source.element) {
-        dom0 = script.source.element.class !== "HTMLScriptElement";
-      } else {
-        dom0 = false;
-      }
-
-      line = script.startLine;
-      url = script.url;
-
-      // Checking for the string "[native code]" is the only way at this point
-      // to check for native code. Even if this provides a false positive then
-      // grabbing the source code a second time is harmless.
-      if (functionSource === "[object Object]" ||
-          functionSource === "[object XULElement]" ||
-          functionSource.includes("[native code]")) {
-        functionSource =
-          scriptSource.substr(script.sourceStart, script.sourceLength);
-
-        // At this point the script looks like this:
-        // () { ... }
-        // We prefix this with "function" if it is not a fat arrow function.
-        if (!isArrowFunction) {
-          functionSource = "function " + functionSource;
-        }
-      }
-    } else {
-      // If the listener is a native one (provided by C++ code) then we have no
-      // access to the script. We use the native flag to prevent showing the
-      // debugger button because the script is not available.
-      native = true;
-    }
-
-    // Fat arrow function text always contains the parameters. Function
-    // parameters are often missing e.g. if Array.sort is used as a handler.
-    // If they are missing we provide the parameters ourselves.
-    if (parameterNames && parameterNames.length > 0) {
-      let prefix = "function " + name + "()";
-      let paramString = parameterNames.join(", ");
-
-      if (functionSource.startsWith(prefix)) {
-        functionSource = functionSource.substr(prefix.length);
-
-        functionSource = `function ${name} (${paramString})${functionSource}`;
-      }
-    }
-
-    // If the listener is native code we display the filename "[native code]."
-    // This is the official string and should *not* be translated.
-    let origin;
-    if (native) {
-      origin = "[native code]";
-    } else {
-      origin = url + ((dom0 || line === 0) ? "" : ":" + line);
-    }
-
-    let eventObj = {
-      type: override.type || type,
-      handler: override.handler || functionSource.trim(),
-      origin: override.origin || origin,
-      tags: override.tags || tags,
-      DOM0: typeof override.dom0 !== "undefined" ? override.dom0 : dom0,
-      capturing: typeof override.capturing !== "undefined" ?
-                 override.capturing : capturing,
-      hide: typeof override.hide !== "undefined" ? override.hide : hide,
-      native
-    };
-
-    // Hide the debugger icon for DOM0 and native listeners. DOM0 listeners are
-    // generated dynamically from e.g. an onclick="" attribute so the script
-    // doesn't actually exist.
-    if (native || dom0) {
-      eventObj.hide.debugger = true;
-    }
-
-    listenerArray.push(eventObj);
-
-    dbg.removeDebuggee(globalDO);
-  },
-
-  /**
-   * Returns a LongStringActor with the node's value.
-   */
-  getNodeValue: function () {
-    return new LongStringActor(this.conn, this.rawNode.nodeValue || "");
-  },
-
-  /**
-   * Set the node's value to a given string.
-   */
-  setNodeValue: function (value) {
-    this.rawNode.nodeValue = value;
-  },
-
-  /**
-   * Get a unique selector string for this node.
-   */
-  getUniqueSelector: function () {
-    if (Cu.isDeadWrapper(this.rawNode)) {
-      return "";
-    }
-    return findCssSelector(this.rawNode);
-  },
-
-  /**
-   * Get the full CSS path for this node.
-   *
-   * @return {String} A CSS selector with a part for the node and each of its ancestors.
-   */
-  getCssPath: function () {
-    if (Cu.isDeadWrapper(this.rawNode)) {
-      return "";
-    }
-    return getCssPath(this.rawNode);
-  },
-
-  /**
-   * Get the XPath for this node.
-   *
-   * @return {String} The XPath for finding this node on the page.
-   */
-  getXPath: function () {
-    if (Cu.isDeadWrapper(this.rawNode)) {
-      return "";
-    }
-    return getXPath(this.rawNode);
-  },
-
-  /**
-   * Scroll the selected node into view.
-   */
-  scrollIntoView: function () {
-    this.rawNode.scrollIntoView(true);
-  },
-
-  /**
-   * Get the node's image data if any (for canvas and img nodes).
-   * Returns an imageData object with the actual data being a LongStringActor
-   * and a size json object.
-   * The image data is transmitted as a base64 encoded png data-uri.
-   * The method rejects if the node isn't an image or if the image is missing
-   *
-   * Accepts a maxDim request parameter to resize images that are larger. This
-   * is important as the resizing occurs server-side so that image-data being
-   * transfered in the longstring back to the client will be that much smaller
-   */
-  getImageData: function (maxDim) {
-    return imageToImageData(this.rawNode, maxDim).then(imageData => {
-      return {
-        data: LongStringActor(this.conn, imageData.data),
-        size: imageData.size
-      };
-    });
-  },
-
-  /**
-   * Get all event listeners that are listening on this node.
-   */
-  getEventListenerInfo: function () {
-    let node = this.rawNode;
-
-    if (this.rawNode.nodeName.toLowerCase() === "html") {
-      let winListeners = this.getEventListeners(node.ownerGlobal) || [];
-      let docElementListeners = this.getEventListeners(node) || [];
-      let docListeners = this.getEventListeners(node.parentNode) || [];
-
-      return [...winListeners, ...docElementListeners, ...docListeners];
-    }
-    return this.getEventListeners(node);
-  },
-
-  /**
-   * Modify a node's attributes.  Passed an array of modifications
-   * similar in format to "attributes" mutations.
-   * {
-   *   attributeName: <string>
-   *   attributeNamespace: <optional string>
-   *   newValue: <optional string> - If null or undefined, the attribute
-   *     will be removed.
-   * }
-   *
-   * Returns when the modifications have been made.  Mutations will
-   * be queued for any changes made.
-   */
-  modifyAttributes: function (modifications) {
-    let rawNode = this.rawNode;
-    for (let change of modifications) {
-      if (change.newValue == null) {
-        if (change.attributeNamespace) {
-          rawNode.removeAttributeNS(change.attributeNamespace,
-                                    change.attributeName);
-        } else {
-          rawNode.removeAttribute(change.attributeName);
-        }
-      } else if (change.attributeNamespace) {
-        rawNode.setAttributeNS(change.attributeNamespace, change.attributeName,
-                               change.newValue);
-      } else {
-        rawNode.setAttribute(change.attributeName, change.newValue);
-      }
-    }
-  },
-
-  /**
-   * Given the font and fill style, get the image data of a canvas with the
-   * preview text and font.
-   * Returns an imageData object with the actual data being a LongStringActor
-   * and the width of the text as a string.
-   * The image data is transmitted as a base64 encoded png data-uri.
-   */
-  getFontFamilyDataURL: function (font, fillStyle = "black") {
-    let doc = this.rawNode.ownerDocument;
-    let options = {
-      previewText: FONT_FAMILY_PREVIEW_TEXT,
-      previewFontSize: FONT_FAMILY_PREVIEW_TEXT_SIZE,
-      fillStyle: fillStyle
-    };
-    let { dataURL, size } = getFontPreviewData(font, doc, options);
-
-    return { data: LongStringActor(this.conn, dataURL), size: size };
-  },
-
-  /**
-   * Finds the computed background color of the closest parent with
-   * a set background color.
-   * Returns a string with the background color of the form
-   * rgba(r, g, b, a). Defaults to rgba(255, 255, 255, 1) if no
-   * background color is found.
-   */
-  getClosestBackgroundColor: function () {
-    let current = this.rawNode;
-    while (current) {
-      let computedStyle = CssLogic.getComputedStyle(current);
-      let currentStyle = computedStyle.getPropertyValue("background-color");
-      if (colorUtils.isValidCSSColor(currentStyle)) {
-        let currentCssColor = new colorUtils.CssColor(currentStyle);
-        if (!currentCssColor.isTransparent()) {
-          return currentCssColor.rgba;
-        }
-      }
-      current = current.parentNode;
-    }
-    return "rgba(255, 255, 255, 1)";
-  }
-});
-
-/**
- * Server side of a node list as returned by querySelectorAll()
- */
-var NodeListActor = exports.NodeListActor = protocol.ActorClassWithSpec(nodeListSpec, {
-  typeName: "domnodelist",
-
-  initialize: function (walker, nodeList) {
-    protocol.Actor.prototype.initialize.call(this);
-    this.walker = walker;
-    this.nodeList = nodeList || [];
-  },
-
-  destroy: function () {
-    protocol.Actor.prototype.destroy.call(this);
-  },
-
-  /**
-   * Instead of storing a connection object, the NodeActor gets its connection
-   * from its associated walker.
-   */
-  get conn() {
-    return this.walker.conn;
-  },
-
-  /**
-   * Items returned by this actor should belong to the parent walker.
-   */
-  marshallPool: function () {
-    return this.walker;
-  },
-
-  // Returns the JSON representation of this object over the wire.
-  form: function () {
-    return {
-      actor: this.actorID,
-      length: this.nodeList ? this.nodeList.length : 0
-    };
-  },
-
-  /**
-   * Get a single node from the node list.
-   */
-  item: function (index) {
-    return this.walker.attachElement(this.nodeList[index]);
-  },
-
-  /**
-   * Get a range of the items from the node list.
-   */
-  items: function (start = 0, end = this.nodeList.length) {
-    let items = Array.prototype.slice.call(this.nodeList, start, end)
-      .map(item => this.walker._ref(item));
-    return this.walker.attachElements(items);
-  },
-
-  release: function () {}
-});
-
-/**
- * Server side of the DOM walker.
- */
-var WalkerActor = protocol.ActorClassWithSpec(walkerSpec, {
-  /**
-   * Create the WalkerActor
-   * @param DebuggerServerConnection conn
-   *    The server connection.
-   */
-  initialize: function (conn, tabActor, options) {
-    protocol.Actor.prototype.initialize.call(this, conn);
-    this.tabActor = tabActor;
-    this.rootWin = tabActor.window;
-    this.rootDoc = this.rootWin.document;
-    this._refMap = new Map();
-    this._pendingMutations = [];
-    this._activePseudoClassLocks = new Set();
-    this.showAllAnonymousContent = options.showAllAnonymousContent;
-
-    this.walkerSearch = new WalkerSearch(this);
-
-    // Nodes which have been removed from the client's known
-    // ownership tree are considered "orphaned", and stored in
-    // this set.
-    this._orphaned = new Set();
-
-    // The client can tell the walker that it is interested in a node
-    // even when it is orphaned with the `retainNode` method.  This
-    // list contains orphaned nodes that were so retained.
-    this._retainedOrphans = new Set();
-
-    this.onMutations = this.onMutations.bind(this);
-    this.onFrameLoad = this.onFrameLoad.bind(this);
-    this.onFrameUnload = this.onFrameUnload.bind(this);
-    this._throttledEmitNewMutations = throttle(this._emitNewMutations.bind(this),
-      MUTATIONS_THROTTLING_DELAY);
-
-    tabActor.on("will-navigate", this.onFrameUnload);
-    tabActor.on("window-ready", this.onFrameLoad);
-
-    // Ensure that the root document node actor is ready and
-    // managed.
-    this.rootNode = this.document();
-
-    this.layoutChangeObserver = getLayoutChangesObserver(this.tabActor);
-    this._onReflows = this._onReflows.bind(this);
-    this.layoutChangeObserver.on("reflows", this._onReflows);
-    this._onResize = this._onResize.bind(this);
-    this.layoutChangeObserver.on("resize", this._onResize);
-
-    this._onEventListenerChange = this._onEventListenerChange.bind(this);
-    eventListenerService.addListenerChangeListener(this._onEventListenerChange);
-  },
-
-  /**
-   * Callback for eventListenerService.addListenerChangeListener
-   * @param nsISimpleEnumerator changesEnum
-   *    enumerator of nsIEventListenerChange
-   */
-  _onEventListenerChange: function (changesEnum) {
-    let changes = changesEnum.enumerate();
-    while (changes.hasMoreElements()) {
-      let current = changes.getNext().QueryInterface(Ci.nsIEventListenerChange);
-      let target = current.target;
-
-      if (this._refMap.has(target)) {
-        let actor = this.getNode(target);
-        let mutation = {
-          type: "events",
-          target: actor.actorID,
-          hasEventListeners: actor._hasEventListeners
-        };
-        this.queueMutation(mutation);
-      }
-    }
-  },
-
-  // Returns the JSON representation of this object over the wire.
-  form: function () {
-    return {
-      actor: this.actorID,
-      root: this.rootNode.form(),
-      traits: {
-        // FF42+ Inspector starts managing the Walker, while the inspector also
-        // starts cleaning itself up automatically on client disconnection.
-        // So that there is no need to manually release the walker anymore.
-        autoReleased: true,
-        // XXX: It seems silly that we need to tell the front which capabilities
-        // its actor has in this way when the target can use actorHasMethod. If
-        // this was ported to the protocol (Bug 1157048) we could call that
-        // inside of custom front methods and not need to do traits for this.
-        multiFrameQuerySelectorAll: true,
-        textSearch: true,
-      }
-    };
-  },
-
-  toString: function () {
-    return "[WalkerActor " + this.actorID + "]";
-  },
-
-  getDocumentWalker: function (node, whatToShow, skipTo) {
-    // Allow native anon content (like <video> controls) if preffed on
-    let nodeFilter = this.showAllAnonymousContent
-                    ? allAnonymousContentTreeWalkerFilter
-                    : standardTreeWalkerFilter;
-    return new DocumentWalker(node, this.rootWin, whatToShow, nodeFilter, skipTo);
-  },
-
-  destroy: function () {
-    if (this._destroyed) {
-      return;
-    }
-    this._destroyed = true;
-    protocol.Actor.prototype.destroy.call(this);
-    try {
-      this.clearPseudoClassLocks();
-      this._activePseudoClassLocks = null;
-
-      this._hoveredNode = null;
-      this.rootWin = null;
-      this.rootDoc = null;
-      this.rootNode = null;
-      this.layoutHelpers = null;
-      this._orphaned = null;
-      this._retainedOrphans = null;
-      this._refMap = null;
-
-      this.tabActor.off("will-navigate", this.onFrameUnload);
-      this.tabActor.off("window-ready", this.onFrameLoad);
-
-      this.onFrameLoad = null;
-      this.onFrameUnload = null;
-
-      this.walkerSearch.destroy();
-
-      this.layoutChangeObserver.off("reflows", this._onReflows);
-      this.layoutChangeObserver.off("resize", this._onResize);
-      this.layoutChangeObserver = null;
-      releaseLayoutChangesObserver(this.tabActor);
-
-      eventListenerService.removeListenerChangeListener(
-        this._onEventListenerChange);
-
-      this.onMutations = null;
-
-      this.layoutActor = null;
-      this.tabActor = null;
-
-      this.emit("destroyed");
-    } catch (e) {
-      console.error(e);
-    }
-  },
-
-  release: function () {},
-
-  unmanage: function (actor) {
-    if (actor instanceof NodeActor) {
-      if (this._activePseudoClassLocks &&
-          this._activePseudoClassLocks.has(actor)) {
-        this.clearPseudoClassLocks(actor);
-      }
-      this._refMap.delete(actor.rawNode);
-    }
-    protocol.Actor.prototype.unmanage.call(this, actor);
-  },
-
-  /**
-   * Determine if the walker has come across this DOM node before.
-   * @param {DOMNode} rawNode
-   * @return {Boolean}
-   */
-  hasNode: function (rawNode) {
-    return this._refMap.has(rawNode);
-  },
-
-  /**
-   * If the walker has come across this DOM node before, then get the
-   * corresponding node actor.
-   * @param {DOMNode} rawNode
-   * @return {NodeActor}
-   */
-  getNode: function (rawNode) {
-    return this._refMap.get(rawNode);
-  },
-
-  _ref: function (node) {
-    let actor = this.getNode(node);
-    if (actor) {
-      return actor;
-    }
-
-    actor = new NodeActor(this, node);
-
-    // Add the node actor as a child of this walker actor, assigning
-    // it an actorID.
-    this.manage(actor);
-    this._refMap.set(node, actor);
-
-    if (node.nodeType === Ci.nsIDOMNode.DOCUMENT_NODE) {
-      actor.watchDocument(this.onMutations);
-    }
-    return actor;
-  },
-
-  _onReflows: function (reflows) {
-    // Going through the nodes the walker knows about, see which ones have
-    // had their display changed and send a display-change event if any
-    let changes = [];
-    for (let [node, actor] of this._refMap) {
-      if (Cu.isDeadWrapper(node)) {
-        continue;
-      }
-
-      let isDisplayed = actor.isDisplayed;
-      if (isDisplayed !== actor.wasDisplayed) {
-        changes.push(actor);
-        // Updating the original value
-        actor.wasDisplayed = isDisplayed;
-      }
-    }
-
-    if (changes.length) {
-      this.emit("display-change", changes);
-    }
-  },
-
-  /**
-   * When the browser window gets resized, relay the event to the front.
-   */
-  _onResize: function () {
-    this.emit("resize");
-  },
-
-  /**
-   * This is kept for backward-compatibility reasons with older remote targets.
-   * Targets prior to bug 916443.
-   *
-   * pick/cancelPick are used to pick a node on click on the content
-   * document. But in their implementation prior to bug 916443, they don't allow
-   * highlighting on hover.
-   * The client-side now uses the highlighter actor's pick and cancelPick
-   * methods instead. The client-side uses the the highlightable trait found in
-   * the root actor to determine which version of pick to use.
-   *
-   * As for highlight, the new highlighter actor is used instead of the walker's
-   * highlight method. Same here though, the client-side uses the highlightable
-   * trait to dertermine which to use.
-   *
-   * Keeping these actor methods for now allows newer client-side debuggers to
-   * inspect fxos 1.2 remote targets or older firefox desktop remote targets.
-   */
-  pick: function () {},
-  cancelPick: function () {},
-  highlight: function (node) {},
-
-  /**
-   * Ensures that the node is attached and it can be accessed from the root.
-   *
-   * @param {(Node|NodeActor)} nodes The nodes
-   * @return {Object} An object compatible with the disconnectedNode type.
-   */
-  attachElement: function (node) {
-    let { nodes, newParents } = this.attachElements([node]);
-    return {
-      node: nodes[0],
-      newParents: newParents
-    };
-  },
-
-  /**
-   * Ensures that the nodes are attached and they can be accessed from the root.
-   *
-   * @param {(Node[]|NodeActor[])} nodes The nodes
-   * @return {Object} An object compatible with the disconnectedNodeArray type.
-   */
-  attachElements: function (nodes) {
-    let nodeActors = [];
-    let newParents = new Set();
-    for (let node of nodes) {
-      if (!(node instanceof NodeActor)) {
-        // If an anonymous node was passed in and we aren't supposed to know
-        // about it, then consult with the document walker as the source of
-        // truth about which elements exist.
-        if (!this.showAllAnonymousContent && isAnonymous(node)) {
-          node = this.getDocumentWalker(node).currentNode;
-        }
-
-        node = this._ref(node);
-      }
-
-      this.ensurePathToRoot(node, newParents);
-      // If nodes may be an array of raw nodes, we're sure to only have
-      // NodeActors with the following array.
-      nodeActors.push(node);
-    }
-
-    return {
-      nodes: nodeActors,
-      newParents: [...newParents]
-    };
-  },
-
-  /**
-   * Return the document node that contains the given node,
-   * or the root node if no node is specified.
-   * @param NodeActor node
-   *        The node whose document is needed, or null to
-   *        return the root.
-   */
-  document: function (node) {
-    let doc = isNodeDead(node) ? this.rootDoc : nodeDocument(node.rawNode);
-    return this._ref(doc);
-  },
-
-  /**
-   * Return the documentElement for the document containing the
-   * given node.
-   * @param NodeActor node
-   *        The node whose documentElement is requested, or null
-   *        to use the root document.
-   */
-  documentElement: function (node) {
-    let elt = isNodeDead(node)
-              ? this.rootDoc.documentElement
-              : nodeDocument(node.rawNode).documentElement;
-    return this._ref(elt);
-  },
-
-  /**
-   * Return all parents of the given node, ordered from immediate parent
-   * to root.
-   * @param NodeActor node
-   *    The node whose parents are requested.
-   * @param object options
-   *    Named options, including:
-   *    `sameDocument`: If true, parents will be restricted to the same
-   *      document as the node.
-   *    `sameTypeRootTreeItem`: If true, this will not traverse across
-   *     different types of docshells.
-   */
-  parents: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return [];
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let parents = [];
-    let cur;
-    while ((cur = walker.parentNode())) {
-      if (options.sameDocument &&
-          nodeDocument(cur) != nodeDocument(node.rawNode)) {
-        break;
-      }
-
-      if (options.sameTypeRootTreeItem &&
-          nodeDocshell(cur).sameTypeRootTreeItem !=
-          nodeDocshell(node.rawNode).sameTypeRootTreeItem) {
-        break;
-      }
-
-      parents.push(this._ref(cur));
-    }
-    return parents;
-  },
-
-  parentNode: function (node) {
-    let walker = this.getDocumentWalker(node.rawNode);
-    let parent = walker.parentNode();
-    if (parent) {
-      return this._ref(parent);
-    }
-    return null;
-  },
-
-  /**
-   * If the given NodeActor only has a single text node as a child with a text
-   * content small enough to be inlined, return that child's NodeActor.
-   *
-   * @param NodeActor node
-   */
-  inlineTextChild: function (node) {
-    // Quick checks to prevent creating a new walker if possible.
-    if (node.isBeforePseudoElement ||
-        node.isAfterPseudoElement ||
-        node.rawNode.nodeType != Ci.nsIDOMNode.ELEMENT_NODE ||
-        node.rawNode.children.length > 0) {
-      return undefined;
-    }
-
-    let docWalker = this.getDocumentWalker(node.rawNode);
-    let firstChild = docWalker.firstChild();
-
-    // Bail out if:
-    // - more than one child
-    // - unique child is not a text node
-    // - unique child is a text node, but is too long to be inlined
-    if (!firstChild ||
-        docWalker.nextSibling() ||
-        firstChild.nodeType !== Ci.nsIDOMNode.TEXT_NODE ||
-        firstChild.nodeValue.length > gValueSummaryLength
-        ) {
-      return undefined;
-    }
-
-    return this._ref(firstChild);
-  },
-
-  /**
-   * Mark a node as 'retained'.
-   *
-   * A retained node is not released when `releaseNode` is called on its
-   * parent, or when a parent is released with the `cleanup` option to
-   * `getMutations`.
-   *
-   * When a retained node's parent is released, a retained mode is added to
-   * the walker's "retained orphans" list.
-   *
-   * Retained nodes can be deleted by providing the `force` option to
-   * `releaseNode`.  They will also be released when their document
-   * has been destroyed.
-   *
-   * Retaining a node makes no promise about its children;  They can
-   * still be removed by normal means.
-   */
-  retainNode: function (node) {
-    node.retained = true;
-  },
-
-  /**
-   * Remove the 'retained' mark from a node.  If the node was a
-   * retained orphan, release it.
-   */
-  unretainNode: function (node) {
-    node.retained = false;
-    if (this._retainedOrphans.has(node)) {
-      this._retainedOrphans.delete(node);
-      this.releaseNode(node);
-    }
-  },
-
-  /**
-   * Release actors for a node and all child nodes.
-   */
-  releaseNode: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    if (node.retained && !options.force) {
-      this._retainedOrphans.add(node);
-      return;
-    }
-
-    if (node.retained) {
-      // Forcing a retained node to go away.
-      this._retainedOrphans.delete(node);
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-
-    let child = walker.firstChild();
-    while (child) {
-      let childActor = this.getNode(child);
-      if (childActor) {
-        this.releaseNode(childActor, options);
-      }
-      child = walker.nextSibling();
-    }
-
-    node.destroy();
-  },
-
-  /**
-   * Add any nodes between `node` and the walker's root node that have not
-   * yet been seen by the client.
-   */
-  ensurePathToRoot: function (node, newParents = new Set()) {
-    if (!node) {
-      return newParents;
-    }
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let parent = this.getNode(cur);
-      if (!parent) {
-        // This parent didn't exist, so hasn't been seen by the client yet.
-        newParents.add(this._ref(cur));
-      } else {
-        // This parent did exist, so the client knows about it.
-        return newParents;
-      }
-    }
-    return newParents;
-  },
-
-  /**
-   * Return children of the given node.  By default this method will return
-   * all children of the node, but there are options that can restrict this
-   * to a more manageable subset.
-   *
-   * @param NodeActor node
-   *    The node whose children you're curious about.
-   * @param object options
-   *    Named options:
-   *    `maxNodes`: The set of nodes returned by the method will be no longer
-   *       than maxNodes.
-   *    `start`: If a node is specified, the list of nodes will start
-   *       with the given child.  Mutally exclusive with `center`.
-   *    `center`: If a node is specified, the given node will be as centered
-   *       as possible in the list, given how close to the ends of the child
-   *       list it is.  Mutually exclusive with `start`.
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   *
-   * @returns an object with three items:
-   *    hasFirst: true if the first child of the node is included in the list.
-   *    hasLast: true if the last child of the node is included in the list.
-   *    nodes: Child nodes returned by the request.
-   */
-  children: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    if (options.center && options.start) {
-      throw Error("Can't specify both 'center' and 'start' options.");
-    }
-    let maxNodes = options.maxNodes || -1;
-    if (maxNodes == -1) {
-      maxNodes = Number.MAX_VALUE;
-    }
-
-    // We're going to create a few document walkers with the same filter,
-    // make it easier.
-    let getFilteredWalker = documentWalkerNode => {
-      let { whatToShow } = options;
-      // Use SKIP_TO_SIBLING to force the walker to use a sibling of the provided node
-      // in case this one is incompatible with the walker's filter function.
-      return this.getDocumentWalker(documentWalkerNode, whatToShow, SKIP_TO_SIBLING);
-    };
-
-    // Need to know the first and last child.
-    let rawNode = node.rawNode;
-    let firstChild = getFilteredWalker(rawNode).firstChild();
-    let lastChild = getFilteredWalker(rawNode).lastChild();
-
-    if (!firstChild) {
-      // No children, we're done.
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    let start;
-    if (options.center) {
-      start = options.center.rawNode;
-    } else if (options.start) {
-      start = options.start.rawNode;
-    } else {
-      start = firstChild;
-    }
-
-    let nodes = [];
-
-    // Start by reading backward from the starting point if we're centering...
-    let backwardWalker = getFilteredWalker(start);
-    if (backwardWalker.currentNode != firstChild && options.center) {
-      backwardWalker.previousSibling();
-      let backwardCount = Math.floor(maxNodes / 2);
-      let backwardNodes = this._readBackward(backwardWalker, backwardCount);
-      nodes = backwardNodes;
-    }
-
-    // Then read forward by any slack left in the max children...
-    let forwardWalker = getFilteredWalker(start);
-    let forwardCount = maxNodes - nodes.length;
-    nodes = nodes.concat(this._readForward(forwardWalker, forwardCount));
-
-    // If there's any room left, it means we've run all the way to the end.
-    // If we're centering, check if there are more items to read at the front.
-    let remaining = maxNodes - nodes.length;
-    if (options.center && remaining > 0 && nodes[0].rawNode != firstChild) {
-      let firstNodes = this._readBackward(backwardWalker, remaining);
-
-      // Then put it all back together.
-      nodes = firstNodes.concat(nodes);
-    }
-
-    return {
-      hasFirst: nodes[0].rawNode == firstChild,
-      hasLast: nodes[nodes.length - 1].rawNode == lastChild,
-      nodes: nodes
-    };
-  },
-
-  /**
-   * Return siblings of the given node.  By default this method will return
-   * all siblings of the node, but there are options that can restrict this
-   * to a more manageable subset.
-   *
-   * If `start` or `center` are not specified, this method will center on the
-   * node whose siblings are requested.
-   *
-   * @param NodeActor node
-   *    The node whose children you're curious about.
-   * @param object options
-   *    Named options:
-   *    `maxNodes`: The set of nodes returned by the method will be no longer
-   *       than maxNodes.
-   *    `start`: If a node is specified, the list of nodes will start
-   *       with the given child.  Mutally exclusive with `center`.
-   *    `center`: If a node is specified, the given node will be as centered
-   *       as possible in the list, given how close to the ends of the child
-   *       list it is.  Mutually exclusive with `start`.
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   *
-   * @returns an object with three items:
-   *    hasFirst: true if the first child of the node is included in the list.
-   *    hasLast: true if the last child of the node is included in the list.
-   *    nodes: Child nodes returned by the request.
-   */
-  siblings: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    let parentNode = this.getDocumentWalker(node.rawNode, options.whatToShow)
-                         .parentNode();
-    if (!parentNode) {
-      return {
-        hasFirst: true,
-        hasLast: true,
-        nodes: [node]
-      };
-    }
-
-    if (!(options.start || options.center)) {
-      options.center = node;
-    }
-
-    return this.children(this._ref(parentNode), options);
-  },
-
-  /**
-   * Get the next sibling of a given node.  Getting nodes one at a time
-   * might be inefficient, be careful.
-   *
-   * @param object options
-   *    Named options:
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   */
-  nextSibling: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode, options.whatToShow);
-    let sibling = walker.nextSibling();
-    return sibling ? this._ref(sibling) : null;
-  },
-
-  /**
-   * Get the previous sibling of a given node.  Getting nodes one at a time
-   * might be inefficient, be careful.
-   *
-   * @param object options
-   *    Named options:
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   */
-  previousSibling: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode, options.whatToShow);
-    let sibling = walker.previousSibling();
-    return sibling ? this._ref(sibling) : null;
-  },
-
-  /**
-   * Helper function for the `children` method: Read forward in the sibling
-   * list into an array with `count` items, including the current node.
-   */
-  _readForward: function (walker, count) {
-    let ret = [];
-
-    let node = walker.currentNode;
-    do {
-      if (!walker.isSkippedNode(node)) {
-        // The walker can be on a node that would be filtered out if it didn't find any
-        // other node to fallback to.
-        ret.push(this._ref(node));
-      }
-      node = walker.nextSibling();
-    } while (node && --count);
-    return ret;
-  },
-
-  /**
-   * Helper function for the `children` method: Read backward in the sibling
-   * list into an array with `count` items, including the current node.
-   */
-  _readBackward: function (walker, count) {
-    let ret = [];
-
-    let node = walker.currentNode;
-    do {
-      if (!walker.isSkippedNode(node)) {
-        // The walker can be on a node that would be filtered out if it didn't find any
-        // other node to fallback to.
-        ret.push(this._ref(node));
-      }
-      node = walker.previousSibling();
-    } while (node && --count);
-    ret.reverse();
-    return ret;
-  },
-
-  /**
-   * Return the first node in the document that matches the given selector.
-   * See https://developer.mozilla.org/en-US/docs/Web/API/Element.querySelector
-   *
-   * @param NodeActor baseNode
-   * @param string selector
-   */
-  querySelector: function (baseNode, selector) {
-    if (isNodeDead(baseNode)) {
-      return {};
-    }
-
-    let node = baseNode.rawNode.querySelector(selector);
-    if (!node) {
-      return {};
-    }
-
-    return this.attachElement(node);
-  },
-
-  /**
-   * Return a NodeListActor with all nodes that match the given selector.
-   * See https://developer.mozilla.org/en-US/docs/Web/API/Element.querySelectorAll
-   *
-   * @param NodeActor baseNode
-   * @param string selector
-   */
-  querySelectorAll: function (baseNode, selector) {
-    let nodeList = null;
-
-    try {
-      nodeList = baseNode.rawNode.querySelectorAll(selector);
-    } catch (e) {
-      // Bad selector. Do nothing as the selector can come from a searchbox.
-    }
-
-    return new NodeListActor(this, nodeList);
-  },
-
-  /**
-   * Get a list of nodes that match the given selector in all known frames of
-   * the current content page.
-   * @param {String} selector.
-   * @return {Array}
-   */
-  _multiFrameQuerySelectorAll: function (selector) {
-    let nodes = [];
-
-    for (let {document} of this.tabActor.windows) {
-      try {
-        nodes = [...nodes, ...document.querySelectorAll(selector)];
-      } catch (e) {
-        // Bad selector. Do nothing as the selector can come from a searchbox.
-      }
-    }
-
-    return nodes;
-  },
-
-  /**
-   * Return a NodeListActor with all nodes that match the given selector in all
-   * frames of the current content page.
-   * @param {String} selector
-   */
-  multiFrameQuerySelectorAll: function (selector) {
-    return new NodeListActor(this, this._multiFrameQuerySelectorAll(selector));
-  },
-
-  /**
-   * Search the document for a given string.
-   * Results will be searched with the walker-search module (searches through
-   * tag names, attribute names and values, and text contents).
-   *
-   * @returns {searchresult}
-   *            - {NodeList} list
-   *            - {Array<Object>} metadata. Extra information with indices that
-   *                              match up with node list.
-   */
-  search: function (query) {
-    let results = this.walkerSearch.search(query);
-    let nodeList = new NodeListActor(this, results.map(r => r.node));
-
-    return {
-      list: nodeList,
-      metadata: []
-    };
-  },
-
-  /**
-   * Returns a list of matching results for CSS selector autocompletion.
-   *
-   * @param string query
-   *        The selector query being completed
-   * @param string completing
-   *        The exact token being completed out of the query
-   * @param string selectorState
-   *        One of "pseudo", "id", "tag", "class", "null"
-   */
-  getSuggestionsForQuery: function (query, completing, selectorState) {
-    let sugs = {
-      classes: new Map(),
-      tags: new Map(),
-      ids: new Map()
-    };
-    let result = [];
-    let nodes = null;
-    // Filtering and sorting the results so that protocol transfer is miminal.
-    switch (selectorState) {
-      case "pseudo":
-        result = PSEUDO_SELECTORS.filter(item => {
-          return item[0].startsWith(":" + completing);
-        });
-        break;
-
-      case "class":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("[class]");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          for (let className of node.classList) {
-            sugs.classes.set(className, (sugs.classes.get(className)|0) + 1);
-          }
-        }
-        sugs.classes.delete("");
-        sugs.classes.delete(HIDDEN_CLASS);
-        for (let [className, count] of sugs.classes) {
-          if (className.startsWith(completing)) {
-            result.push(["." + CSS.escape(className), count, selectorState]);
-          }
-        }
-        break;
-
-      case "id":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("[id]");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          sugs.ids.set(node.id, (sugs.ids.get(node.id)|0) + 1);
-        }
-        for (let [id, count] of sugs.ids) {
-          if (id.startsWith(completing) && id !== "") {
-            result.push(["#" + CSS.escape(id), count, selectorState]);
-          }
-        }
-        break;
-
-      case "tag":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("*");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          let tag = node.localName;
-          sugs.tags.set(tag, (sugs.tags.get(tag)|0) + 1);
-        }
-        for (let [tag, count] of sugs.tags) {
-          if ((new RegExp("^" + completing + ".*", "i")).test(tag)) {
-            result.push([tag, count, selectorState]);
-          }
-        }
-
-        // For state 'tag' (no preceding # or .) and when there's no query (i.e.
-        // only one word) then search for the matching classes and ids
-        if (!query) {
-          result = [
-            ...result,
-            ...this.getSuggestionsForQuery(null, completing, "class")
-                   .suggestions,
-            ...this.getSuggestionsForQuery(null, completing, "id")
-                   .suggestions
-          ];
-        }
-
-        break;
-
-      case "null":
-        nodes = this._multiFrameQuerySelectorAll(query);
-        for (let node of nodes) {
-          sugs.ids.set(node.id, (sugs.ids.get(node.id)|0) + 1);
-          let tag = node.localName;
-          sugs.tags.set(tag, (sugs.tags.get(tag)|0) + 1);
-          for (let className of node.classList) {
-            sugs.classes.set(className, (sugs.classes.get(className)|0) + 1);
-          }
-        }
-        for (let [tag, count] of sugs.tags) {
-          tag && result.push([tag, count]);
-        }
-        for (let [id, count] of sugs.ids) {
-          id && result.push(["#" + id, count]);
-        }
-        sugs.classes.delete("");
-        sugs.classes.delete(HIDDEN_CLASS);
-        for (let [className, count] of sugs.classes) {
-          className && result.push(["." + className, count]);
-        }
-    }
-
-    // Sort by count (desc) and name (asc)
-    result = result.sort((a, b) => {
-      // Computed a sortable string with first the inverted count, then the name
-      let sortA = (10000 - a[1]) + a[0];
-      let sortB = (10000 - b[1]) + b[0];
-
-      // Prefixing ids, classes and tags, to group results
-      let firstA = a[0].substring(0, 1);
-      let firstB = b[0].substring(0, 1);
-
-      if (firstA === "#") {
-        sortA = "2" + sortA;
-      } else if (firstA === ".") {
-        sortA = "1" + sortA;
-      } else {
-        sortA = "0" + sortA;
-      }
-
-      if (firstB === "#") {
-        sortB = "2" + sortB;
-      } else if (firstB === ".") {
-        sortB = "1" + sortB;
-      } else {
-        sortB = "0" + sortB;
-      }
-
-      // String compare
-      return sortA.localeCompare(sortB);
-    });
-
-    result.slice(0, 25);
-
-    return {
-      query: query,
-      suggestions: result
-    };
-  },
-
-  /**
-   * Add a pseudo-class lock to a node.
-   *
-   * @param NodeActor node
-   * @param string pseudo
-   *    A pseudoclass: ':hover', ':active', ':focus'
-   * @param options
-   *    Options object:
-   *    `parents`: True if the pseudo-class should be added
-   *      to parent nodes.
-   *    `enabled`: False if the pseudo-class should be locked
-   *      to 'off'. Defaults to true.
-   *
-   * @returns An empty packet.  A "pseudoClassLock" mutation will
-   *    be queued for any changed nodes.
-   */
-  addPseudoClassLock: function (node, pseudo, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    // There can be only one node locked per pseudo, so dismiss all existing
-    // ones
-    for (let locked of this._activePseudoClassLocks) {
-      if (InspectorUtils.hasPseudoClassLock(locked.rawNode, pseudo)) {
-        this._removePseudoClassLock(locked, pseudo);
-      }
-    }
-
-    let enabled = options.enabled === undefined ||
-                  options.enabled;
-    this._addPseudoClassLock(node, pseudo, enabled);
-
-    if (!options.parents) {
-      return;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let curNode = this._ref(cur);
-      this._addPseudoClassLock(curNode, pseudo, enabled);
-    }
-  },
-
-  _queuePseudoClassMutation: function (node) {
-    this.queueMutation({
-      target: node.actorID,
-      type: "pseudoClassLock",
-      pseudoClassLocks: node.writePseudoClassLocks()
-    });
-  },
-
-  _addPseudoClassLock: function (node, pseudo, enabled) {
-    if (node.rawNode.nodeType !== Ci.nsIDOMNode.ELEMENT_NODE) {
-      return false;
-    }
-    InspectorUtils.addPseudoClassLock(node.rawNode, pseudo, enabled);
-    this._activePseudoClassLocks.add(node);
-    this._queuePseudoClassMutation(node);
-    return true;
-  },
-
-  hideNode: function (node) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    loadSheet(node.rawNode.ownerGlobal, HELPER_SHEET);
-    node.rawNode.classList.add(HIDDEN_CLASS);
-  },
-
-  unhideNode: function (node) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    node.rawNode.classList.remove(HIDDEN_CLASS);
-  },
-
-  /**
-   * Remove a pseudo-class lock from a node.
-   *
-   * @param NodeActor node
-   * @param string pseudo
-   *    A pseudoclass: ':hover', ':active', ':focus'
-   * @param options
-   *    Options object:
-   *    `parents`: True if the pseudo-class should be removed
-   *      from parent nodes.
-   *
-   * @returns An empty response.  "pseudoClassLock" mutations
-   *    will be emitted for any changed nodes.
-   */
-  removePseudoClassLock: function (node, pseudo, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    this._removePseudoClassLock(node, pseudo);
-
-    // Remove pseudo class for children as we don't want to allow
-    // turning it on for some childs without setting it on some parents
-    for (let locked of this._activePseudoClassLocks) {
-      if (node.rawNode.contains(locked.rawNode) &&
-          InspectorUtils.hasPseudoClassLock(locked.rawNode, pseudo)) {
-        this._removePseudoClassLock(locked, pseudo);
-      }
-    }
-
-    if (!options.parents) {
-      return;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let curNode = this._ref(cur);
-      this._removePseudoClassLock(curNode, pseudo);
-    }
-  },
-
-  _removePseudoClassLock: function (node, pseudo) {
-    if (node.rawNode.nodeType != Ci.nsIDOMNode.ELEMENT_NODE) {
-      return false;
-    }
-    InspectorUtils.removePseudoClassLock(node.rawNode, pseudo);
-    if (!node.writePseudoClassLocks()) {
-      this._activePseudoClassLocks.delete(node);
-    }
-
-    this._queuePseudoClassMutation(node);
-    return true;
-  },
-
-  /**
-   * Clear all the pseudo-classes on a given node or all nodes.
-   * @param {NodeActor} node Optional node to clear pseudo-classes on
-   */
-  clearPseudoClassLocks: function (node) {
-    if (node && isNodeDead(node)) {
-      return;
-    }
-
-    if (node) {
-      InspectorUtils.clearPseudoClassLocks(node.rawNode);
-      this._activePseudoClassLocks.delete(node);
-      this._queuePseudoClassMutation(node);
-    } else {
-      for (let locked of this._activePseudoClassLocks) {
-        InspectorUtils.clearPseudoClassLocks(locked.rawNode);
-        this._activePseudoClassLocks.delete(locked);
-        this._queuePseudoClassMutation(locked);
-      }
-    }
-  },
-
-  /**
-   * Get a node's innerHTML property.
-   */
-  innerHTML: function (node) {
-    let html = "";
-    if (!isNodeDead(node)) {
-      html = node.rawNode.innerHTML;
-    }
-    return LongStringActor(this.conn, html);
-  },
-
-  /**
-   * Set a node's innerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   * @param {string} value The piece of HTML content.
-   */
-  setInnerHTML: function (node, value) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    let rawNode = node.rawNode;
-    if (rawNode.nodeType !== rawNode.ownerDocument.ELEMENT_NODE) {
-      throw new Error("Can only change innerHTML to element nodes");
-    }
-    // eslint-disable-next-line no-unsanitized/property
-    rawNode.innerHTML = value;
-  },
-
-  /**
-   * Get a node's outerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   */
-  outerHTML: function (node) {
-    let outerHTML = "";
-    if (!isNodeDead(node)) {
-      outerHTML = node.rawNode.outerHTML;
-    }
-    return LongStringActor(this.conn, outerHTML);
-  },
-
-  /**
-   * Set a node's outerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   * @param {string} value The piece of HTML content.
-   */
-  setOuterHTML: function (node, value) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    let parsedDOM = DOMParser.parseFromString(value, "text/html");
-    let rawNode = node.rawNode;
-    let parentNode = rawNode.parentNode;
-
-    // Special case for head and body.  Setting document.body.outerHTML
-    // creates an extra <head> tag, and document.head.outerHTML creates
-    // an extra <body>.  So instead we will call replaceChild with the
-    // parsed DOM, assuming that they aren't trying to set both tags at once.
-    if (rawNode.tagName === "BODY") {
-      if (parsedDOM.head.innerHTML === "") {
-        parentNode.replaceChild(parsedDOM.body, rawNode);
-      } else {
-      // eslint-disable-next-line no-unsanitized/property
-        rawNode.outerHTML = value;
-      }
-    } else if (rawNode.tagName === "HEAD") {
-      if (parsedDOM.body.innerHTML === "") {
-        parentNode.replaceChild(parsedDOM.head, rawNode);
-      } else {
-        // eslint-disable-next-line no-unsanitized/property
-        rawNode.outerHTML = value;
-      }
-    } else if (node.isDocumentElement()) {
-      // Unable to set outerHTML on the document element.  Fall back by
-      // setting attributes manually, then replace the body and head elements.
-      let finalAttributeModifications = [];
-      let attributeModifications = {};
-      for (let attribute of rawNode.attributes) {
-        attributeModifications[attribute.name] = null;
-      }
-      for (let attribute of parsedDOM.documentElement.attributes) {
-        attributeModifications[attribute.name] = attribute.value;
-      }
-      for (let key in attributeModifications) {
-        finalAttributeModifications.push({
-          attributeName: key,
-          newValue: attributeModifications[key]
-        });
-      }
-      node.modifyAttributes(finalAttributeModifications);
-      rawNode.replaceChild(parsedDOM.head, rawNode.querySelector("head"));
-      rawNode.replaceChild(parsedDOM.body, rawNode.querySelector("body"));
-    } else {
-      // eslint-disable-next-line no-unsanitized/property
-      rawNode.outerHTML = value;
-    }
-  },
-
-  /**
-   * Insert adjacent HTML to a node.
-   *
-   * @param {Node} node
-   * @param {string} position One of "beforeBegin", "afterBegin", "beforeEnd",
-   *                          "afterEnd" (see Element.insertAdjacentHTML).
-   * @param {string} value The HTML content.
-   */
-  insertAdjacentHTML: function (node, position, value) {
-    if (isNodeDead(node)) {
-      return {node: [], newParents: []};
-    }
-
-    let rawNode = node.rawNode;
-    let isInsertAsSibling = position === "beforeBegin" ||
-      position === "afterEnd";
-
-    // Don't insert anything adjacent to the document element.
-    if (isInsertAsSibling && node.isDocumentElement()) {
-      throw new Error("Can't insert adjacent element to the root.");
-    }
-
-    let rawParentNode = rawNode.parentNode;
-    if (!rawParentNode && isInsertAsSibling) {
-      throw new Error("Can't insert as sibling without parent node.");
-    }
-
-    // We can't use insertAdjacentHTML, because we want to return the nodes
-    // being created (so the front can remove them if the user undoes
-    // the change). So instead, use Range.createContextualFragment().
-    let range = rawNode.ownerDocument.createRange();
-    if (position === "beforeBegin" || position === "afterEnd") {
-      range.selectNode(rawNode);
-    } else {
-      range.selectNodeContents(rawNode);
-    }
-    let docFrag = range.createContextualFragment(value);
-    let newRawNodes = Array.from(docFrag.childNodes);
-    switch (position) {
-      case "beforeBegin":
-        rawParentNode.insertBefore(docFrag, rawNode);
-        break;
-      case "afterEnd":
-        // Note: if the second argument is null, rawParentNode.insertBefore
-        // behaves like rawParentNode.appendChild.
-        rawParentNode.insertBefore(docFrag, rawNode.nextSibling);
-        break;
-      case "afterBegin":
-        rawNode.insertBefore(docFrag, rawNode.firstChild);
-        break;
-      case "beforeEnd":
-        rawNode.appendChild(docFrag);
-        break;
-      default:
-        throw new Error("Invalid position value. Must be either " +
-          "'beforeBegin', 'beforeEnd', 'afterBegin' or 'afterEnd'.");
-    }
-
-    return this.attachElements(newRawNodes);
-  },
-
-  /**
-   * Duplicate a specified node
-   *
-   * @param {NodeActor} node The node to duplicate.
-   */
-  duplicateNode: function ({rawNode}) {
-    let clonedNode = rawNode.cloneNode(true);
-    rawNode.parentNode.insertBefore(clonedNode, rawNode.nextSibling);
-  },
-
-  /**
-   * Test whether a node is a document or a document element.
-   *
-   * @param {NodeActor} node The node to remove.
-   * @return {boolean} True if the node is a document or a document element.
-   */
-  isDocumentOrDocumentElementNode: function (node) {
-    return ((node.rawNode.ownerDocument &&
-      node.rawNode.ownerDocument.documentElement === this.rawNode) ||
-      node.rawNode.nodeType === Ci.nsIDOMNode.DOCUMENT_NODE);
-  },
-
-  /**
-   * Removes a node from its parent node.
-   *
-   * @param {NodeActor} node The node to remove.
-   * @returns The node's nextSibling before it was removed.
-   */
-  removeNode: function (node) {
-    if (isNodeDead(node) || this.isDocumentOrDocumentElementNode(node)) {
-      throw Error("Cannot remove document, document elements or dead nodes.");
-    }
-
-    let nextSibling = this.nextSibling(node);
-    node.rawNode.remove();
-    // Mutation events will take care of the rest.
-    return nextSibling;
-  },
-
-  /**
-   * Removes an array of nodes from their parent node.
-   *
-   * @param {NodeActor[]} nodes The nodes to remove.
-   */
-  removeNodes: function (nodes) {
-    // Check that all nodes are valid before processing the removals.
-    for (let node of nodes) {
-      if (isNodeDead(node) || this.isDocumentOrDocumentElementNode(node)) {
-        throw Error("Cannot remove document, document elements or dead nodes");
-      }
-    }
-
-    for (let node of nodes) {
-      node.rawNode.remove();
-      // Mutation events will take care of the rest.
-    }
-  },
-
-  /**
-   * Insert a node into the DOM.
-   */
-  insertBefore: function (node, parent, sibling) {
-    if (isNodeDead(node) ||
-        isNodeDead(parent) ||
-        (sibling && isNodeDead(sibling))) {
-      return;
-    }
-
-    let rawNode = node.rawNode;
-    let rawParent = parent.rawNode;
-    let rawSibling = sibling ? sibling.rawNode : null;
-
-    // Don't bother inserting a node if the document position isn't going
-    // to change. This prevents needless iframes reloading and mutations.
-    if (rawNode.parentNode === rawParent) {
-      let currentNextSibling = this.nextSibling(node);
-      currentNextSibling = currentNextSibling ? currentNextSibling.rawNode :
-                                                null;
-
-      if (rawNode === rawSibling || currentNextSibling === rawSibling) {
-        return;
-      }
-    }
-
-    rawParent.insertBefore(rawNode, rawSibling);
-  },
-
-  /**
-   * Editing a node's tagname actually means creating a new node with the same
-   * attributes, removing the node and inserting the new one instead.
-   * This method does not return anything as mutation events are taking care of
-   * informing the consumers about changes.
-   */
-  editTagName: function (node, tagName) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let oldNode = node.rawNode;
-
-    // Create a new element with the same attributes as the current element and
-    // prepare to replace the current node with it.
-    let newNode;
-    try {
-      newNode = nodeDocument(oldNode).createElement(tagName);
-    } catch (x) {
-      // Failed to create a new element with that tag name, ignore the change,
-      // and signal the error to the front.
-      return Promise.reject(new Error("Could not change node's tagName to " + tagName));
-    }
-
-    let attrs = oldNode.attributes;
-    for (let i = 0; i < attrs.length; i++) {
-      newNode.setAttribute(attrs[i].name, attrs[i].value);
-    }
-
-    // Insert the new node, and transfer the old node's children.
-    oldNode.parentNode.insertBefore(newNode, oldNode);
-    while (oldNode.firstChild) {
-      newNode.appendChild(oldNode.firstChild);
-    }
-
-    oldNode.remove();
-    return null;
-  },
-
-  /**
-   * Get any pending mutation records.  Must be called by the client after
-   * the `new-mutations` notification is received.  Returns an array of
-   * mutation records.
-   *
-   * Mutation records have a basic structure:
-   *
-   * {
-   *   type: attributes|characterData|childList,
-   *   target: <domnode actor ID>,
-   * }
-   *
-   * And additional attributes based on the mutation type:
-   *
-   * `attributes` type:
-   *   attributeName: <string> - the attribute that changed
-   *   attributeNamespace: <string> - the attribute's namespace URI, if any.
-   *   newValue: <string> - The new value of the attribute, if any.
-   *
-   * `characterData` type:
-   *   newValue: <string> - the new nodeValue for the node
-   *
-   * `childList` type is returned when the set of children for a node
-   * has changed.  Includes extra data, which can be used by the client to
-   * maintain its ownership subtree.
-   *
-   *   added: array of <domnode actor ID> - The list of actors *previously
-   *     seen by the client* that were added to the target node.
-   *   removed: array of <domnode actor ID> The list of actors *previously
-   *     seen by the client* that were removed from the target node.
-   *   inlineTextChild: If the node now has a single text child, it will
-   *     be sent here.
-   *
-   * Actors that are included in a MutationRecord's `removed` but
-   * not in an `added` have been removed from the client's ownership
-   * tree (either by being moved under a node the client has seen yet
-   * or by being removed from the tree entirely), and is considered
-   * 'orphaned'.
-   *
-   * Keep in mind that if a node that the client hasn't seen is moved
-   * into or out of the target node, it will not be included in the
-   * removedNodes and addedNodes list, so if the client is interested
-   * in the new set of children it needs to issue a `children` request.
-   */
-  getMutations: function (options = {}) {
-    let pending = this._pendingMutations || [];
-    this._pendingMutations = [];
-    this._waitingForGetMutations = false;
-
-    if (options.cleanup) {
-      for (let node of this._orphaned) {
-        // Release the orphaned node.  Nodes or children that have been
-        // retained will be moved to this._retainedOrphans.
-        this.releaseNode(node);
-      }
-      this._orphaned = new Set();
-    }
-
-    return pending;
-  },
-
-  queueMutation: function (mutation) {
-    if (!this.actorID || this._destroyed) {
-      // We've been destroyed, don't bother queueing this mutation.
-      return;
-    }
-
-    // Add the mutation to the list of mutations to be retrieved next.
-    this._pendingMutations.push(mutation);
-
-    // Bail out if we already emitted a new-mutations event and are waiting for a client
-    // to retrieve them.
-    if (this._waitingForGetMutations) {
-      return;
-    }
-
-    if (IMMEDIATE_MUTATIONS.includes(mutation.type)) {
-      this._emitNewMutations();
-    } else {
-      /**
-       * If many mutations are fired at the same time, clients might sequentially request
-       * children/siblings for updated nodes, which can be costly. By throttling the calls
-       * to getMutations, duplicated mutations will be ignored.
-       */
-      this._throttledEmitNewMutations();
-    }
-  },
-
-  _emitNewMutations: function () {
-    if (!this.actorID || this._destroyed) {
-      // Bail out if the actor was destroyed after throttling this call.
-      return;
-    }
-
-    if (this._waitingForGetMutations || this._pendingMutations.length == 0) {
-      // Bail out if we already fired the new-mutation event or if no mutations are
-      // waiting to be retrieved.
-      return;
-    }
-
-    this._waitingForGetMutations = true;
-    this.emit("new-mutations");
-  },
-
-  /**
-   * Handles mutations from the DOM mutation observer API.
-   *
-   * @param array[MutationRecord] mutations
-   *    See https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver#MutationRecord
-   */
-  onMutations: function (mutations) {
-    // Notify any observers that want *all* mutations (even on nodes that aren't
-    // referenced).  This is not sent over the protocol so can only be used by
-    // scripts running in the server process.
-    this.emit("any-mutation");
-
-    for (let change of mutations) {
-      let targetActor = this.getNode(change.target);
-      if (!targetActor) {
-        continue;
-      }
-      let targetNode = change.target;
-      let type = change.type;
-      let mutation = {
-        type: type,
-        target: targetActor.actorID,
-      };
-
-      if (type === "attributes") {
-        mutation.attributeName = change.attributeName;
-        mutation.attributeNamespace = change.attributeNamespace || undefined;
-        mutation.newValue = targetNode.hasAttribute(mutation.attributeName) ?
-                            targetNode.getAttribute(mutation.attributeName)
-                            : null;
-      } else if (type === "characterData") {
-        mutation.newValue = targetNode.nodeValue;
-        this._maybeQueueInlineTextChildMutation(change, targetNode);
-      } else if (type === "childList" || type === "nativeAnonymousChildList") {
-        // Get the list of removed and added actors that the client has seen
-        // so that it can keep its ownership tree up to date.
-        let removedActors = [];
-        let addedActors = [];
-        for (let removed of change.removedNodes) {
-          let removedActor = this.getNode(removed);
-          if (!removedActor) {
-            // If the client never encountered this actor we don't need to
-            // mention that it was removed.
-            continue;
-          }
-          // While removed from the tree, nodes are saved as orphaned.
-          this._orphaned.add(removedActor);
-          removedActors.push(removedActor.actorID);
-        }
-        for (let added of change.addedNodes) {
-          let addedActor = this.getNode(added);
-          if (!addedActor) {
-            // If the client never encounted this actor we don't need to tell
-            // it about its addition for ownership tree purposes - if the
-            // client wants to see the new nodes it can ask for children.
-            continue;
-          }
-          // The actor is reconnected to the ownership tree, unorphan
-          // it and let the client know so that its ownership tree is up
-          // to date.
-          this._orphaned.delete(addedActor);
-          addedActors.push(addedActor.actorID);
-        }
-
-        mutation.numChildren = targetActor.numChildren;
-        mutation.removed = removedActors;
-        mutation.added = addedActors;
-
-        let inlineTextChild = this.inlineTextChild(targetActor);
-        if (inlineTextChild) {
-          mutation.inlineTextChild = inlineTextChild.form();
-        }
-      }
-      this.queueMutation(mutation);
-    }
-  },
-
-  /**
-   * Check if the provided mutation could change the way the target element is
-   * inlined with its parent node. If it might, a custom mutation of type
-   * "inlineTextChild" will be queued.
-   *
-   * @param {MutationRecord} mutation
-   *        A characterData type mutation
-   */
-  _maybeQueueInlineTextChildMutation: function (mutation) {
-    let {oldValue, target} = mutation;
-    let newValue = target.nodeValue;
-    let limit = gValueSummaryLength;
-
-    if ((oldValue.length <= limit && newValue.length <= limit) ||
-        (oldValue.length > limit && newValue.length > limit)) {
-      // Bail out if the new & old values are both below/above the size limit.
-      return;
-    }
-
-    let parentActor = this.getNode(target.parentNode);
-    if (!parentActor || parentActor.rawNode.children.length > 0) {
-      // If the parent node has other children, a character data mutation will
-      // not change anything regarding inlining text nodes.
-      return;
-    }
-
-    let inlineTextChild = this.inlineTextChild(parentActor);
-    this.queueMutation({
-      type: "inlineTextChild",
-      target: parentActor.actorID,
-      inlineTextChild:
-        inlineTextChild ? inlineTextChild.form() : undefined
-    });
-  },
-
-  onFrameLoad: function ({ window, isTopLevel }) {
-    let { readyState } = window.document;
-    if (readyState != "interactive" && readyState != "complete") {
-      window.addEventListener("DOMContentLoaded",
-        this.onFrameLoad.bind(this, { window, isTopLevel }),
-        { once: true });
-      return;
-    }
-    if (isTopLevel) {
-      // If we initialize the inspector while the document is loading,
-      // we may already have a root document set in the constructor.
-      if (this.rootDoc && !Cu.isDeadWrapper(this.rootDoc) &&
-          this.rootDoc.defaultView) {
-        this.onFrameUnload({ window: this.rootDoc.defaultView });
-      }
-      // Update all DOM objects references to target the new document.
-      this.rootWin = window;
-      this.rootDoc = window.document;
-      this.rootNode = this.document();
-      this.queueMutation({
-        type: "newRoot",
-        target: this.rootNode.form()
-      });
-      return;
-    }
-    let frame = getFrameElement(window);
-    let frameActor = this.getNode(frame);
-    if (!frameActor) {
-      return;
-    }
-
-    this.queueMutation({
-      type: "frameLoad",
-      target: frameActor.actorID,
-    });
-
-    // Send a childList mutation on the frame.
-    this.queueMutation({
-      type: "childList",
-      target: frameActor.actorID,
-      added: [],
-      removed: []
-    });
-  },
-
-  // Returns true if domNode is in window or a subframe.
-  _childOfWindow: function (window, domNode) {
-    let win = nodeDocument(domNode).defaultView;
-    while (win) {
-      if (win === window) {
-        return true;
-      }
-      win = getFrameElement(win);
-    }
-    return false;
-  },
-
-  onFrameUnload: function ({ window }) {
-    // Any retained orphans that belong to this document
-    // or its children need to be released, and a mutation sent
-    // to notify of that.
-    let releasedOrphans = [];
-
-    for (let retained of this._retainedOrphans) {
-      if (Cu.isDeadWrapper(retained.rawNode) ||
-          this._childOfWindow(window, retained.rawNode)) {
-        this._retainedOrphans.delete(retained);
-        releasedOrphans.push(retained.actorID);
-        this.releaseNode(retained, { force: true });
-      }
-    }
-
-    if (releasedOrphans.length > 0) {
-      this.queueMutation({
-        target: this.rootNode.actorID,
-        type: "unretained",
-        nodes: releasedOrphans
-      });
-    }
-
-    let doc = window.document;
-    let documentActor = this.getNode(doc);
-    if (!documentActor) {
-      return;
-    }
-
-    if (this.rootDoc === doc) {
-      this.rootDoc = null;
-      this.rootNode = null;
-    }
-
-    this.queueMutation({
-      type: "documentUnload",
-      target: documentActor.actorID
-    });
-
-    let walker = this.getDocumentWalker(doc);
-    let parentNode = walker.parentNode();
-    if (parentNode) {
-      // Send a childList mutation on the frame so that clients know
-      // they should reread the children list.
-      this.queueMutation({
-        type: "childList",
-        target: this.getNode(parentNode).actorID,
-        added: [],
-        removed: []
-      });
-    }
-
-    // Need to force a release of this node, because those nodes can't
-    // be accessed anymore.
-    this.releaseNode(documentActor, { force: true });
-  },
-
-  /**
-   * Check if a node is attached to the DOM tree of the current page.
-   * @param {nsIDomNode} rawNode
-   * @return {Boolean} false if the node is removed from the tree or within a
-   * document fragment
-   */
-  _isInDOMTree: function (rawNode) {
-    let walker = this.getDocumentWalker(rawNode);
-    let current = walker.currentNode;
-
-    // Reaching the top of tree
-    while (walker.parentNode()) {
-      current = walker.currentNode;
-    }
-
-    // The top of the tree is a fragment or is not rootDoc, hence rawNode isn't
-    // attached
-    if (current.nodeType === Ci.nsIDOMNode.DOCUMENT_FRAGMENT_NODE ||
-        current !== this.rootDoc) {
-      return false;
-    }
-
-    // Otherwise the top of the tree is rootDoc, hence rawNode is in rootDoc
-    return true;
-  },
-
-  /**
-   * @see _isInDomTree
-   */
-  isInDOMTree: function (node) {
-    if (isNodeDead(node)) {
-      return false;
-    }
-    return this._isInDOMTree(node.rawNode);
-  },
-
-  /**
-   * Given an ObjectActor (identified by its ID), commonly used in the debugger,
-   * webconsole and variablesView, return the corresponding inspector's
-   * NodeActor
-   */
-  getNodeActorFromObjectActor: function (objectActorID) {
-    let actor = this.conn.getActor(objectActorID);
-    if (!actor) {
-      return null;
-    }
-
-    let debuggerObject = this.conn.getActor(objectActorID).obj;
-    let rawNode = debuggerObject.unsafeDereference();
-
-    if (!this._isInDOMTree(rawNode)) {
-      return null;
-    }
-
-    // This is a special case for the document object whereby it is considered
-    // as document.documentElement (the <html> node)
-    if (rawNode.defaultView && rawNode === rawNode.defaultView.document) {
-      rawNode = rawNode.documentElement;
-    }
-
-    return this.attachElement(rawNode);
-  },
-
-  /**
-   * Given a windowID return the NodeActor for the corresponding frameElement,
-   * unless it's the root window
-   */
-  getNodeActorFromWindowID: function (windowID) {
-    let win;
-
-    try {
-      win = Services.wm.getOuterWindowWithId(windowID);
-    } catch (e) {
-      // ignore
-    }
-
-    if (!win) {
-      return { error: "noWindow",
-               message: "The related docshell is destroyed or not found" };
-    } else if (!win.frameElement) {
-      // the frame element of the root document is privileged & thus
-      // inaccessible, so return the document body/element instead
-      return this.attachElement(win.document.body || win.document.documentElement);
-    }
-
-    return this.attachElement(win.frameElement);
-  },
-
-  /**
-   * Given a StyleSheetActor (identified by its ID), commonly used in the
-   * style-editor, get its ownerNode and return the corresponding walker's
-   * NodeActor.
-   * Note that getNodeFromActor was added later and can now be used instead.
-   */
-  getStyleSheetOwnerNode: function (styleSheetActorID) {
-    return this.getNodeFromActor(styleSheetActorID, ["ownerNode"]);
-  },
-
-  /**
-   * This method can be used to retrieve NodeActor for DOM nodes from other
-   * actors in a way that they can later be highlighted in the page, or
-   * selected in the inspector.
-   * If an actor has a reference to a DOM node, and the UI needs to know about
-   * this DOM node (and possibly select it in the inspector), the UI should
-   * first retrieve a reference to the walkerFront:
-   *
-   * // Make sure the inspector/walker have been initialized first.
-   * toolbox.initInspector().then(() => {
-   *  // Retrieve the walker.
-   *  let walker = toolbox.walker;
-   * });
-   *
-   * And then call this method:
-   *
-   * // Get the nodeFront from my actor, passing the ID and properties path.
-   * walker.getNodeFromActor(myActorID, ["element"]).then(nodeFront => {
-   *   // Use the nodeFront, e.g. select the node in the inspector.
-   *   toolbox.getPanel("inspector").selection.setNodeFront(nodeFront);
-   * });
-   *
-   * @param {String} actorID The ID for the actor that has a reference to the
-   * DOM node.
-   * @param {Array} path Where, on the actor, is the DOM node stored. If in the
-   * scope of the actor, the node is available as `this.data.node`, then this
-   * should be ["data", "node"].
-   * @return {NodeActor} The attached NodeActor, or null if it couldn't be
-   * found.
-   */
-  getNodeFromActor: function (actorID, path) {
-    let actor = this.conn.getActor(actorID);
-    if (!actor) {
-      return null;
-    }
-
-    let obj = actor;
-    for (let name of path) {
-      if (!(name in obj)) {
-        return null;
-      }
-      obj = obj[name];
-    }
-
-    return this.attachElement(obj);
-  },
-
-  /**
-   * Returns an instance of the LayoutActor that is used to retrieve CSS layout-related
-   * information.
-   *
-   * @return {LayoutActor}
-   */
-  getLayoutInspector: function () {
-    if (!this.layoutActor) {
-      this.layoutActor = new LayoutActor(this.conn, this.tabActor, this);
-    }
-
-    return this.layoutActor;
-  },
-
-  /**
-   * Returns the offset parent DOMNode of the given node if it exists, otherwise, it
-   * returns null.
-   */
-  getOffsetParent: function (node) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let offsetParent = node.rawNode.offsetParent;
-
-    if (!offsetParent) {
-      return null;
-    }
-
-    return this._ref(offsetParent);
-  },
-});
 
 /**
  * Server side of the inspector actor, which is used to create
  * inspector-related actors, including the walker.
  */
 exports.InspectorActor = protocol.ActorClassWithSpec(inspectorSpec, {
   initialize: function (conn, tabActor) {
     protocol.Actor.prototype.initialize.call(this, conn);
@@ -2902,36 +197,36 @@ exports.InspectorActor = protocol.ActorC
    * is important as the resizing occurs server-side so that image-data being
    * transfered in the longstring back to the client will be that much smaller
    */
   getImageDataFromURL: function (url, maxDim) {
     let img = new this.window.Image();
     img.src = url;
 
     // imageToImageData waits for the image to load.
-    return imageToImageData(img, maxDim).then(imageData => {
+    return InspectorActorUtils.imageToImageData(img, maxDim).then(imageData => {
       return {
         data: LongStringActor(this.conn, imageData.data),
         size: imageData.size
       };
     });
   },
 
   /**
    * Resolve a URL to its absolute form, in the scope of a given content window.
    * @param {String} url.
    * @param {NodeActor} node If provided, the owner window of this node will be
    * used to resolve the URL. Otherwise, the top-level content window will be
    * used instead.
    * @return {String} url.
    */
   resolveRelativeURL: function (url, node) {
-    let document = isNodeDead(node)
+    let document = InspectorActorUtils.isNodeDead(node)
                    ? this.window.document
-                   : nodeDocument(node.rawNode);
+                   : InspectorActorUtils.nodeDocument(node.rawNode);
 
     if (!document) {
       return url;
     }
 
     let baseURI = Services.io.newURI(document.location.href);
     return Services.io.newURI(url, null, baseURI).spec;
   },
@@ -3014,389 +309,8 @@ exports.InspectorActor = protocol.ActorC
   _onColorPicked: function (e, color) {
     this.emit("color-picked", color);
   },
 
   _onColorPickCanceled: function () {
     this.emit("color-pick-canceled");
   }
 });
-
-// Exported for test purposes.
-exports._documentWalker = DocumentWalker;
-
-function nodeDocument(node) {
-  if (Cu.isDeadWrapper(node)) {
-    return null;
-  }
-  return node.ownerDocument ||
-         (node.nodeType == Ci.nsIDOMNode.DOCUMENT_NODE ? node : null);
-}
-
-function nodeDocshell(node) {
-  let doc = node ? nodeDocument(node) : null;
-  let win = doc ? doc.defaultView : null;
-  if (win) {
-    return win.QueryInterface(Ci.nsIInterfaceRequestor)
-              .getInterface(Ci.nsIDocShell);
-  }
-  return null;
-}
-
-function isNodeDead(node) {
-  return !node || !node.rawNode || Cu.isDeadWrapper(node.rawNode);
-}
-
-/**
- * Wrapper for inDeepTreeWalker.  Adds filtering to the traversal methods.
- * See inDeepTreeWalker for more information about the methods.
- *
- * @param {DOMNode} node
- * @param {Window} rootWin
- * @param {Number} whatToShow
- *        See nodeFilterConstants / inIDeepTreeWalker for options.
- * @param {Function} filter
- *        A custom filter function Taking in a DOMNode and returning an Int. See
- *        WalkerActor.nodeFilter for an example.
- * @param {String} skipTo
- *        Either SKIP_TO_PARENT or SKIP_TO_SIBLING. If the provided node is not compatible
- *        with the filter function for this walker, try to find a compatible one either
- *        in the parents or in the siblings of the node.
- */
-function DocumentWalker(node, rootWin,
-    whatToShow = nodeFilterConstants.SHOW_ALL,
-    filter = standardTreeWalkerFilter,
-    skipTo = SKIP_TO_PARENT) {
-  if (Cu.isDeadWrapper(rootWin) || !rootWin.location) {
-    throw new Error("Got an invalid root window in DocumentWalker");
-  }
-
-  this.walker = Cc["@mozilla.org/inspector/deep-tree-walker;1"]
-    .createInstance(Ci.inIDeepTreeWalker);
-  this.walker.showAnonymousContent = true;
-  this.walker.showSubDocuments = true;
-  this.walker.showDocumentsAsNodes = true;
-  this.walker.init(rootWin.document, whatToShow);
-  this.filter = filter;
-
-  // Make sure that the walker knows about the initial node (which could
-  // be skipped due to a filter).
-  this.walker.currentNode = this.getStartingNode(node, skipTo);
-}
-
-DocumentWalker.prototype = {
-  get whatToShow() {
-    return this.walker.whatToShow;
-  },
-  get currentNode() {
-    return this.walker.currentNode;
-  },
-  set currentNode(val) {
-    this.walker.currentNode = val;
-  },
-
-  parentNode: function () {
-    return this.walker.parentNode();
-  },
-
-  nextNode: function () {
-    let node = this.walker.currentNode;
-    if (!node) {
-      return null;
-    }
-
-    let nextNode = this.walker.nextNode();
-    while (nextNode && this.isSkippedNode(nextNode)) {
-      nextNode = this.walker.nextNode();
-    }
-
-    return nextNode;
-  },
-
-  firstChild: function () {
-    let node = this.walker.currentNode;
-    if (!node) {
-      return null;
-    }
-
-    let firstChild = this.walker.firstChild();
-    while (firstChild && this.isSkippedNode(firstChild)) {
-      firstChild = this.walker.nextSibling();
-    }
-
-    return firstChild;
-  },
-
-  lastChild: function () {
-    let node = this.walker.currentNode;
-    if (!node) {
-      return null;
-    }
-
-    let lastChild = this.walker.lastChild();
-    while (lastChild && this.isSkippedNode(lastChild)) {
-      lastChild = this.walker.previousSibling();
-    }
-
-    return lastChild;
-  },
-
-  previousSibling: function () {
-    let node = this.walker.previousSibling();
-    while (node && this.isSkippedNode(node)) {
-      node = this.walker.previousSibling();
-    }
-    return node;
-  },
-
-  nextSibling: function () {
-    let node = this.walker.nextSibling();
-    while (node && this.isSkippedNode(node)) {
-      node = this.walker.nextSibling();
-    }
-    return node;
-  },
-
-  getStartingNode: function (node, skipTo) {
-    // Keep a reference on the starting node in case we can't find a node compatible with
-    // the filter.
-    let startingNode = node;
-
-    if (skipTo === SKIP_TO_PARENT) {
-      while (node && this.isSkippedNode(node)) {
-        node = node.parentNode;
-      }
-    } else if (skipTo === SKIP_TO_SIBLING) {
-      node = this.getClosestAcceptedSibling(node);
-    }
-
-    return node || startingNode;
-  },
-
-  /**
-   * Loop on all of the provided node siblings until finding one that is compliant with
-   * the filter function.
-   */
-  getClosestAcceptedSibling: function (node) {
-    if (this.filter(node) === nodeFilterConstants.FILTER_ACCEPT) {
-      // node is already valid, return immediately.
-      return node;
-    }
-
-    // Loop on starting node siblings.
-    let previous = node;
-    let next = node;
-    while (previous || next) {
-      previous = previous && previous.previousSibling;
-      next = next && next.nextSibling;
-
-      if (previous && this.filter(previous) === nodeFilterConstants.FILTER_ACCEPT) {
-        // A valid node was found in the previous siblings of the node.
-        return previous;
-      }
-
-      if (next && this.filter(next) === nodeFilterConstants.FILTER_ACCEPT) {
-        // A valid node was found in the next siblings of the node.
-        return next;
-      }
-    }
-
-    return null;
-  },
-
-  isSkippedNode: function (node) {
-    return this.filter(node) === nodeFilterConstants.FILTER_SKIP;
-  },
-};
-
-function isInXULDocument(el) {
-  let doc = nodeDocument(el);
-  return doc &&
-         doc.documentElement &&
-         doc.documentElement.namespaceURI === XUL_NS;
-}
-
-/**
- * This DeepTreeWalker filter skips whitespace text nodes and anonymous
- * content with the exception of ::before and ::after and anonymous content
- * in XUL document (needed to show all elements in the browser toolbox).
- */
-function standardTreeWalkerFilter(node) {
-  // ::before and ::after are native anonymous content, but we always
-  // want to show them
-  if (node.nodeName === "_moz_generated_content_before" ||
-      node.nodeName === "_moz_generated_content_after") {
-    return nodeFilterConstants.FILTER_ACCEPT;
-  }
-
-  // Ignore empty whitespace text nodes that do not impact the layout.
-  if (isWhitespaceTextNode(node)) {
-    return nodeHasSize(node)
-           ? nodeFilterConstants.FILTER_ACCEPT
-           : nodeFilterConstants.FILTER_SKIP;
-  }
-
-  // Ignore all native and XBL anonymous content inside a non-XUL document.
-  // We need to do this to skip things like form controls, scrollbars,
-  // video controls, etc (see bug 1187482).
-  if (!isInXULDocument(node) && (isXBLAnonymous(node) ||
-                                  isNativeAnonymous(node))) {
-    return nodeFilterConstants.FILTER_SKIP;
-  }
-
-  return nodeFilterConstants.FILTER_ACCEPT;
-}
-
-/**
- * This DeepTreeWalker filter is like standardTreeWalkerFilter except that
- * it also includes all anonymous content (like internal form controls).
- */
-function allAnonymousContentTreeWalkerFilter(node) {
-  // Ignore empty whitespace text nodes that do not impact the layout.
-  if (isWhitespaceTextNode(node)) {
-    return nodeHasSize(node)
-           ? nodeFilterConstants.FILTER_ACCEPT
-           : nodeFilterConstants.FILTER_SKIP;
-  }
-  return nodeFilterConstants.FILTER_ACCEPT;
-}
-
-/**
- * Is the given node a text node composed of whitespace only?
- * @param {DOMNode} node
- * @return {Boolean}
- */
-function isWhitespaceTextNode(node) {
-  return node.nodeType == Ci.nsIDOMNode.TEXT_NODE && !/[^\s]/.exec(node.nodeValue);
-}
-
-/**
- * Does the given node have non-0 width and height?
- * @param {DOMNode} node
- * @return {Boolean}
- */
-function nodeHasSize(node) {
-  if (!node.getBoxQuads) {
-    return false;
-  }
-
-  let quads = node.getBoxQuads();
-  return quads.length && quads.some(quad => quad.bounds.width && quad.bounds.height);
-}
-
-/**
- * Returns a promise that is settled once the given HTMLImageElement has
- * finished loading.
- *
- * @param {HTMLImageElement} image - The image element.
- * @param {Number} timeout - Maximum amount of time the image is allowed to load
- * before the waiting is aborted. Ignored if flags.testing is set.
- *
- * @return {Promise} that is fulfilled once the image has loaded. If the image
- * fails to load or the load takes too long, the promise is rejected.
- */
-function ensureImageLoaded(image, timeout) {
-  let { HTMLImageElement } = image.ownerGlobal;
-  if (!(image instanceof HTMLImageElement)) {
-    return promise.reject("image must be an HTMLImageELement");
-  }
-
-  if (image.complete) {
-    // The image has already finished loading.
-    return promise.resolve();
-  }
-
-  // This image is still loading.
-  let onLoad = AsyncUtils.listenOnce(image, "load");
-
-  // Reject if loading fails.
-  let onError = AsyncUtils.listenOnce(image, "error").then(() => {
-    return promise.reject("Image '" + image.src + "' failed to load.");
-  });
-
-  // Don't timeout when testing. This is never settled.
-  let onAbort = new Promise(() => {});
-
-  if (!flags.testing) {
-    // Tests are not running. Reject the promise after given timeout.
-    onAbort = DevToolsUtils.waitForTime(timeout).then(() => {
-      return promise.reject("Image '" + image.src + "' took too long to load.");
-    });
-  }
-
-  // See which happens first.
-  return promise.race([onLoad, onError, onAbort]);
-}
-
-/**
- * Given an <img> or <canvas> element, return the image data-uri. If @param node
- * is an <img> element, the method waits a while for the image to load before
- * the data is generated. If the image does not finish loading in a reasonable
- * time (IMAGE_FETCHING_TIMEOUT milliseconds) the process aborts.
- *
- * @param {HTMLImageElement|HTMLCanvasElement} node - The <img> or <canvas>
- * element, or Image() object. Other types cause the method to reject.
- * @param {Number} maxDim - Optionally pass a maximum size you want the longest
- * side of the image to be resized to before getting the image data.
-
- * @return {Promise} A promise that is fulfilled with an object containing the
- * data-uri and size-related information:
- * { data: "...",
- *   size: {
- *     naturalWidth: 400,
- *     naturalHeight: 300,
- *     resized: true }
- *  }.
- *
- * If something goes wrong, the promise is rejected.
- */
-var imageToImageData = Task.async(function* (node, maxDim) {
-  let { HTMLCanvasElement, HTMLImageElement } = node.ownerGlobal;
-
-  let isImg = node instanceof HTMLImageElement;
-  let isCanvas = node instanceof HTMLCanvasElement;
-
-  if (!isImg && !isCanvas) {
-    throw new Error("node is not a <canvas> or <img> element.");
-  }
-
-  if (isImg) {
-    // Ensure that the image is ready.
-    yield ensureImageLoaded(node, IMAGE_FETCHING_TIMEOUT);
-  }
-
-  // Get the image resize ratio if a maxDim was provided
-  let resizeRatio = 1;
-  let imgWidth = node.naturalWidth || node.width;
-  let imgHeight = node.naturalHeight || node.height;
-  let imgMax = Math.max(imgWidth, imgHeight);
-  if (maxDim && imgMax > maxDim) {
-    resizeRatio = maxDim / imgMax;
-  }
-
-  // Extract the image data
-  let imageData;
-  // The image may already be a data-uri, in which case, save ourselves the
-  // trouble of converting via the canvas.drawImage.toDataURL method, but only
-  // if the image doesn't need resizing
-  if (isImg && node.src.startsWith("data:") && resizeRatio === 1) {
-    imageData = node.src;
-  } else {
-    // Create a canvas to copy the rawNode into and get the imageData from
-    let canvas = node.ownerDocument.createElementNS(XHTML_NS, "canvas");
-    canvas.width = imgWidth * resizeRatio;
-    canvas.height = imgHeight * resizeRatio;
-    let ctx = canvas.getContext("2d");
-
-    // Copy the rawNode image or canvas in the new canvas and extract data
-    ctx.drawImage(node, 0, 0, canvas.width, canvas.height);
-    imageData = canvas.toDataURL("image/png");
-  }
-
-  return {
-    data: imageData,
-    size: {
-      naturalWidth: imgWidth,
-      naturalHeight: imgHeight,
-      resized: resizeRatio !== 1
-    }
-  };
-});
--- a/devtools/server/actors/inspector/moz.build
+++ b/devtools/server/actors/inspector/moz.build
@@ -1,12 +1,16 @@
 # -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
 # vim: set filetype=python:
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 DevToolsModules(
-    'inspector.js',
+  'document-walker.js',
+  'inspector.js',
+  'node-actor.js',
+  'utils.js',
+  'walker-actor.js',
 )
 
 with Files('**'):
     BUG_COMPONENT = ('Firefox', 'Developer Tools: Inspector')
copy from devtools/server/actors/inspector/inspector.js
copy to devtools/server/actors/inspector/node-actor.js
--- a/devtools/server/actors/inspector/inspector.js
+++ b/devtools/server/actors/inspector/node-actor.js
@@ -1,213 +1,48 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
-/**
- * Here's the server side of the remote inspector.
- *
- * The WalkerActor is the client's view of the debuggee's DOM.  It's gives
- * the client a tree of NodeActor objects.
- *
- * The walker presents the DOM tree mostly unmodified from the source DOM
- * tree, but with a few key differences:
- *
- *  - Empty text nodes are ignored.  This is pretty typical of developer
- *    tools, but maybe we should reconsider that on the server side.
- *  - iframes with documents loaded have the loaded document as the child,
- *    the walker provides one big tree for the whole document tree.
- *
- * There are a few ways to get references to NodeActors:
- *
- *   - When you first get a WalkerActor reference, it comes with a free
- *     reference to the root document's node.
- *   - Given a node, you can ask for children, siblings, and parents.
- *   - You can issue querySelector and querySelectorAll requests to find
- *     other elements.
- *   - Requests that return arbitrary nodes from the tree (like querySelector
- *     and querySelectorAll) will also return any nodes the client hasn't
- *     seen in order to have a complete set of parents.
- *
- * Once you have a NodeFront, you should be able to answer a few questions
- * without further round trips, like the node's name, namespace/tagName,
- * attributes, etc.  Other questions (like a text node's full nodeValue)
- * might require another round trip.
- *
- * The protocol guarantees that the client will always know the parent of
- * any node that is returned by the server.  This means that some requests
- * (like querySelector) will include the extra nodes needed to satisfy this
- * requirement.  The client keeps track of this parent relationship, so the
- * node fronts form a tree that is a subset of the actual DOM tree.
- *
- *
- * We maintain this guarantee to support the ability to release subtrees on
- * the client - when a node is disconnected from the DOM tree we want to be
- * able to free the client objects for all the children nodes.
- *
- * So to be able to answer "all the children of a given node that we have
- * seen on the client side", we guarantee that every time we've seen a node,
- * we connect it up through its parents.
- */
+const {Ci, Cu} = require("chrome");
 
-const {Cc, Ci, Cu} = require("chrome");
-const Services = require("Services");
 const protocol = require("devtools/shared/protocol");
-const {LongStringActor} = require("devtools/server/actors/string");
-const promise = require("promise");
-const defer = require("devtools/shared/defer");
-const {Task} = require("devtools/shared/task");
-const EventEmitter = require("devtools/shared/event-emitter");
+const {nodeSpec, nodeListSpec} = require("devtools/shared/specs/node");
+
 const InspectorUtils = require("InspectorUtils");
 
-const {walkerSpec, inspectorSpec} = require("devtools/shared/specs/inspector");
-const {nodeSpec, nodeListSpec} = require("devtools/shared/specs/node");
+loader.lazyRequireGetter(this, "colorUtils", "devtools/shared/css/color", true);
 
-loader.lazyRequireGetter(this, "DevToolsUtils", "devtools/shared/DevToolsUtils");
-loader.lazyRequireGetter(this, "AsyncUtils", "devtools/shared/async-utils");
-loader.lazyRequireGetter(this, "CssLogic", "devtools/server/css-logic", true);
-loader.lazyRequireGetter(this, "findCssSelector", "devtools/shared/inspector/css-logic", true);
 loader.lazyRequireGetter(this, "getCssPath", "devtools/shared/inspector/css-logic", true);
 loader.lazyRequireGetter(this, "getXPath", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "colorUtils", "devtools/shared/css/color", true);
-loader.lazyRequireGetter(this, "EyeDropper", "devtools/server/actors/highlighters/eye-dropper", true);
-loader.lazyRequireGetter(this, "WalkerSearch", "devtools/server/actors/utils/walker-search", true);
-loader.lazyRequireGetter(this, "PageStyleActor", "devtools/server/actors/styles", true);
-loader.lazyRequireGetter(this, "getFontPreviewData", "devtools/server/actors/styles", true);
-loader.lazyRequireGetter(this, "flags", "devtools/shared/flags");
-loader.lazyRequireGetter(this, "throttle", "devtools/shared/throttle", true);
-loader.lazyRequireGetter(this, "LayoutActor", "devtools/server/actors/layout", true);
-loader.lazyRequireGetter(this, "HighlighterActor", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "CustomHighlighterActor", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "isTypeRegistered", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "HighlighterEnvironment", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "EventParsers", "devtools/server/event-parsers", true);
-loader.lazyRequireGetter(this, "isAnonymous", "devtools/shared/layout/utils", true);
+loader.lazyRequireGetter(this, "findCssSelector", "devtools/shared/inspector/css-logic", true);
+
 loader.lazyRequireGetter(this, "isNativeAnonymous", "devtools/shared/layout/utils", true);
 loader.lazyRequireGetter(this, "isXBLAnonymous", "devtools/shared/layout/utils", true);
 loader.lazyRequireGetter(this, "isShadowAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "getFrameElement", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "loadSheet", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "getLayoutChangesObserver", "devtools/server/actors/reflow", true);
-loader.lazyRequireGetter(this, "releaseLayoutChangesObserver", "devtools/server/actors/reflow", true);
-loader.lazyRequireGetter(this, "nodeFilterConstants", "devtools/shared/dom-node-filter-constants");
+loader.lazyRequireGetter(this, "isAnonymous", "devtools/shared/layout/utils", true);
 
-loader.lazyServiceGetter(this, "DOMParser",
-  "@mozilla.org/xmlextras/domparser;1", "nsIDOMParser");
+loader.lazyRequireGetter(this, "InspectorActorUtils", "devtools/server/actors/inspector/utils");
+loader.lazyRequireGetter(this, "LongStringActor", "devtools/server/actors/string", true);
+loader.lazyRequireGetter(this, "getFontPreviewData", "devtools/server/actors/styles", true);
+loader.lazyRequireGetter(this, "CssLogic", "devtools/server/css-logic", true);
+loader.lazyRequireGetter(this, "EventParsers", "devtools/server/event-parsers", true);
 
-loader.lazyServiceGetter(this, "eventListenerService",
-  "@mozilla.org/eventlistenerservice;1", "nsIEventListenerService");
+const EventEmitter = require("devtools/shared/event-emitter");
 
+const PSEUDO_CLASSES = [":hover", ":active", ":focus"];
 const FONT_FAMILY_PREVIEW_TEXT = "The quick brown fox jumps over the lazy dog";
 const FONT_FAMILY_PREVIEW_TEXT_SIZE = 20;
-const PSEUDO_CLASSES = [":hover", ":active", ":focus"];
-const HIDDEN_CLASS = "__fx-devtools-hide-shortcut__";
-const SVG_NS = "http://www.w3.org/2000/svg";
-const XHTML_NS = "http://www.w3.org/1999/xhtml";
-const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
-const IMAGE_FETCHING_TIMEOUT = 500;
-
-// Minimum delay between two "new-mutations" events.
-const MUTATIONS_THROTTLING_DELAY = 100;
-// List of mutation types that should -not- be throttled.
-const IMMEDIATE_MUTATIONS = [
-  "documentUnload",
-  "frameLoad",
-  "newRoot",
-  "pseudoClassLock",
-];
-
-// SKIP_TO_* arguments are used with the DocumentWalker, driving the strategy to use if
-// the starting node is incompatible with the filter function of the walker.
-const SKIP_TO_PARENT = "SKIP_TO_PARENT";
-const SKIP_TO_SIBLING = "SKIP_TO_SIBLING";
-
-// The possible completions to a ':' with added score to give certain values
-// some preference.
-const PSEUDO_SELECTORS = [
-  [":active", 1],
-  [":hover", 1],
-  [":focus", 1],
-  [":visited", 0],
-  [":link", 0],
-  [":first-letter", 0],
-  [":first-child", 2],
-  [":before", 2],
-  [":after", 2],
-  [":lang(", 0],
-  [":not(", 3],
-  [":first-of-type", 0],
-  [":last-of-type", 0],
-  [":only-of-type", 0],
-  [":only-child", 2],
-  [":nth-child(", 3],
-  [":nth-last-child(", 0],
-  [":nth-of-type(", 0],
-  [":nth-last-of-type(", 0],
-  [":last-child", 2],
-  [":root", 0],
-  [":empty", 0],
-  [":target", 0],
-  [":enabled", 0],
-  [":disabled", 0],
-  [":checked", 1],
-  ["::selection", 0]
-];
-
-var HELPER_SHEET = "data:text/css;charset=utf-8," + encodeURIComponent(`
-  .__fx-devtools-hide-shortcut__ {
-    visibility: hidden !important;
-  }
-
-  :-moz-devtools-highlighted {
-    outline: 2px dashed #F06!important;
-    outline-offset: -2px !important;
-  }
-`);
-
-/**
- * We only send nodeValue up to a certain size by default.  This stuff
- * controls that size.
- */
-exports.DEFAULT_VALUE_SUMMARY_LENGTH = 50;
-var gValueSummaryLength = exports.DEFAULT_VALUE_SUMMARY_LENGTH;
-
-exports.getValueSummaryLength = function () {
-  return gValueSummaryLength;
-};
-
-exports.setValueSummaryLength = function (val) {
-  gValueSummaryLength = val;
-};
-
-/**
- * Returns the properly cased version of the node's tag name, which can be
- * used when displaying said name in the UI.
- *
- * @param  {Node} rawNode
- *         Node for which we want the display name
- * @return {String}
- *         Properly cased version of the node tag name
- */
-const getNodeDisplayName = function (rawNode) {
-  if (rawNode.nodeName && !rawNode.localName) {
-    // The localName & prefix APIs have been moved from the Node interface to the Element
-    // interface. Use Node.nodeName as a fallback.
-    return rawNode.nodeName;
-  }
-  return (rawNode.prefix ? rawNode.prefix + ":" : "") + rawNode.localName;
-};
-exports.getNodeDisplayName = getNodeDisplayName;
 
 /**
  * Server side of the node actor.
  */
-var NodeActor = exports.NodeActor = protocol.ActorClassWithSpec(nodeSpec, {
+const NodeActor = protocol.ActorClassWithSpec(nodeSpec, {
   initialize: function (walker, node) {
     protocol.Actor.prototype.initialize.call(this, null);
     this.walker = walker;
     this.rawNode = node;
     this._eventParsers = new EventParsers().parsers;
 
     // Storing the original display of the node, to track changes when reflows
     // occur
@@ -257,17 +92,17 @@ var NodeActor = exports.NodeActor = prot
     let form = {
       actor: this.actorID,
       baseURI: this.rawNode.baseURI,
       parent: parentNode ? parentNode.actorID : undefined,
       nodeType: this.rawNode.nodeType,
       namespaceURI: this.rawNode.namespaceURI,
       nodeName: this.rawNode.nodeName,
       nodeValue: this.rawNode.nodeValue,
-      displayName: getNodeDisplayName(this.rawNode),
+      displayName: InspectorActorUtils.getNodeDisplayName(this.rawNode),
       numChildren: this.numChildren,
       inlineTextChild: inlineTextChild ? inlineTextChild.form() : undefined,
 
       // doctype attributes
       name: this.rawNode.name,
       publicId: this.rawNode.publicId,
       systemId: this.rawNode.systemId,
 
@@ -372,17 +207,17 @@ var NodeActor = exports.NodeActor = prot
     return CssLogic.getComputedStyle(this.rawNode);
   },
 
   /**
    * Is the node's display computed style value other than "none"
    */
   get isDisplayed() {
     // Consider all non-element nodes as displayed.
-    if (isNodeDead(this) ||
+    if (InspectorActorUtils.isNodeDead(this) ||
         this.rawNode.nodeType !== Ci.nsIDOMNode.ELEMENT_NODE ||
         this.isAfterPseudoElement ||
         this.isBeforePseudoElement) {
       return true;
     }
 
     let style = this.computedStyle;
     if (!style) {
@@ -696,17 +531,17 @@ var NodeActor = exports.NodeActor = prot
    * The image data is transmitted as a base64 encoded png data-uri.
    * The method rejects if the node isn't an image or if the image is missing
    *
    * Accepts a maxDim request parameter to resize images that are larger. This
    * is important as the resizing occurs server-side so that image-data being
    * transfered in the longstring back to the client will be that much smaller
    */
   getImageData: function (maxDim) {
-    return imageToImageData(this.rawNode, maxDim).then(imageData => {
+    return InspectorActorUtils.imageToImageData(this.rawNode, maxDim).then(imageData => {
       return {
         data: LongStringActor(this.conn, imageData.data),
         size: imageData.size
       };
     });
   },
 
   /**
@@ -798,17 +633,17 @@ var NodeActor = exports.NodeActor = prot
     }
     return "rgba(255, 255, 255, 1)";
   }
 });
 
 /**
  * Server side of a node list as returned by querySelectorAll()
  */
-var NodeListActor = exports.NodeListActor = protocol.ActorClassWithSpec(nodeListSpec, {
+const NodeListActor = protocol.ActorClassWithSpec(nodeListSpec, {
   typeName: "domnodelist",
 
   initialize: function (walker, nodeList) {
     protocol.Actor.prototype.initialize.call(this);
     this.walker = walker;
     this.nodeList = nodeList || [];
   },
 
@@ -853,2550 +688,10 @@ var NodeListActor = exports.NodeListActo
     let items = Array.prototype.slice.call(this.nodeList, start, end)
       .map(item => this.walker._ref(item));
     return this.walker.attachElements(items);
   },
 
   release: function () {}
 });
 
-/**
- * Server side of the DOM walker.
- */
-var WalkerActor = protocol.ActorClassWithSpec(walkerSpec, {
-  /**
-   * Create the WalkerActor
-   * @param DebuggerServerConnection conn
-   *    The server connection.
-   */
-  initialize: function (conn, tabActor, options) {
-    protocol.Actor.prototype.initialize.call(this, conn);
-    this.tabActor = tabActor;
-    this.rootWin = tabActor.window;
-    this.rootDoc = this.rootWin.document;
-    this._refMap = new Map();
-    this._pendingMutations = [];
-    this._activePseudoClassLocks = new Set();
-    this.showAllAnonymousContent = options.showAllAnonymousContent;
-
-    this.walkerSearch = new WalkerSearch(this);
-
-    // Nodes which have been removed from the client's known
-    // ownership tree are considered "orphaned", and stored in
-    // this set.
-    this._orphaned = new Set();
-
-    // The client can tell the walker that it is interested in a node
-    // even when it is orphaned with the `retainNode` method.  This
-    // list contains orphaned nodes that were so retained.
-    this._retainedOrphans = new Set();
-
-    this.onMutations = this.onMutations.bind(this);
-    this.onFrameLoad = this.onFrameLoad.bind(this);
-    this.onFrameUnload = this.onFrameUnload.bind(this);
-    this._throttledEmitNewMutations = throttle(this._emitNewMutations.bind(this),
-      MUTATIONS_THROTTLING_DELAY);
-
-    tabActor.on("will-navigate", this.onFrameUnload);
-    tabActor.on("window-ready", this.onFrameLoad);
-
-    // Ensure that the root document node actor is ready and
-    // managed.
-    this.rootNode = this.document();
-
-    this.layoutChangeObserver = getLayoutChangesObserver(this.tabActor);
-    this._onReflows = this._onReflows.bind(this);
-    this.layoutChangeObserver.on("reflows", this._onReflows);
-    this._onResize = this._onResize.bind(this);
-    this.layoutChangeObserver.on("resize", this._onResize);
-
-    this._onEventListenerChange = this._onEventListenerChange.bind(this);
-    eventListenerService.addListenerChangeListener(this._onEventListenerChange);
-  },
-
-  /**
-   * Callback for eventListenerService.addListenerChangeListener
-   * @param nsISimpleEnumerator changesEnum
-   *    enumerator of nsIEventListenerChange
-   */
-  _onEventListenerChange: function (changesEnum) {
-    let changes = changesEnum.enumerate();
-    while (changes.hasMoreElements()) {
-      let current = changes.getNext().QueryInterface(Ci.nsIEventListenerChange);
-      let target = current.target;
-
-      if (this._refMap.has(target)) {
-        let actor = this.getNode(target);
-        let mutation = {
-          type: "events",
-          target: actor.actorID,
-          hasEventListeners: actor._hasEventListeners
-        };
-        this.queueMutation(mutation);
-      }
-    }
-  },
-
-  // Returns the JSON representation of this object over the wire.
-  form: function () {
-    return {
-      actor: this.actorID,
-      root: this.rootNode.form(),
-      traits: {
-        // FF42+ Inspector starts managing the Walker, while the inspector also
-        // starts cleaning itself up automatically on client disconnection.
-        // So that there is no need to manually release the walker anymore.
-        autoReleased: true,
-        // XXX: It seems silly that we need to tell the front which capabilities
-        // its actor has in this way when the target can use actorHasMethod. If
-        // this was ported to the protocol (Bug 1157048) we could call that
-        // inside of custom front methods and not need to do traits for this.
-        multiFrameQuerySelectorAll: true,
-        textSearch: true,
-      }
-    };
-  },
-
-  toString: function () {
-    return "[WalkerActor " + this.actorID + "]";
-  },
-
-  getDocumentWalker: function (node, whatToShow, skipTo) {
-    // Allow native anon content (like <video> controls) if preffed on
-    let nodeFilter = this.showAllAnonymousContent
-                    ? allAnonymousContentTreeWalkerFilter
-                    : standardTreeWalkerFilter;
-    return new DocumentWalker(node, this.rootWin, whatToShow, nodeFilter, skipTo);
-  },
-
-  destroy: function () {
-    if (this._destroyed) {
-      return;
-    }
-    this._destroyed = true;
-    protocol.Actor.prototype.destroy.call(this);
-    try {
-      this.clearPseudoClassLocks();
-      this._activePseudoClassLocks = null;
-
-      this._hoveredNode = null;
-      this.rootWin = null;
-      this.rootDoc = null;
-      this.rootNode = null;
-      this.layoutHelpers = null;
-      this._orphaned = null;
-      this._retainedOrphans = null;
-      this._refMap = null;
-
-      this.tabActor.off("will-navigate", this.onFrameUnload);
-      this.tabActor.off("window-ready", this.onFrameLoad);
-
-      this.onFrameLoad = null;
-      this.onFrameUnload = null;
-
-      this.walkerSearch.destroy();
-
-      this.layoutChangeObserver.off("reflows", this._onReflows);
-      this.layoutChangeObserver.off("resize", this._onResize);
-      this.layoutChangeObserver = null;
-      releaseLayoutChangesObserver(this.tabActor);
-
-      eventListenerService.removeListenerChangeListener(
-        this._onEventListenerChange);
-
-      this.onMutations = null;
-
-      this.layoutActor = null;
-      this.tabActor = null;
-
-      this.emit("destroyed");
-    } catch (e) {
-      console.error(e);
-    }
-  },
-
-  release: function () {},
-
-  unmanage: function (actor) {
-    if (actor instanceof NodeActor) {
-      if (this._activePseudoClassLocks &&
-          this._activePseudoClassLocks.has(actor)) {
-        this.clearPseudoClassLocks(actor);
-      }
-      this._refMap.delete(actor.rawNode);
-    }
-    protocol.Actor.prototype.unmanage.call(this, actor);
-  },
-
-  /**
-   * Determine if the walker has come across this DOM node before.
-   * @param {DOMNode} rawNode
-   * @return {Boolean}
-   */
-  hasNode: function (rawNode) {
-    return this._refMap.has(rawNode);
-  },
-
-  /**
-   * If the walker has come across this DOM node before, then get the
-   * corresponding node actor.
-   * @param {DOMNode} rawNode
-   * @return {NodeActor}
-   */
-  getNode: function (rawNode) {
-    return this._refMap.get(rawNode);
-  },
-
-  _ref: function (node) {
-    let actor = this.getNode(node);
-    if (actor) {
-      return actor;
-    }
-
-    actor = new NodeActor(this, node);
-
-    // Add the node actor as a child of this walker actor, assigning
-    // it an actorID.
-    this.manage(actor);
-    this._refMap.set(node, actor);
-
-    if (node.nodeType === Ci.nsIDOMNode.DOCUMENT_NODE) {
-      actor.watchDocument(this.onMutations);
-    }
-    return actor;
-  },
-
-  _onReflows: function (reflows) {
-    // Going through the nodes the walker knows about, see which ones have
-    // had their display changed and send a display-change event if any
-    let changes = [];
-    for (let [node, actor] of this._refMap) {
-      if (Cu.isDeadWrapper(node)) {
-        continue;
-      }
-
-      let isDisplayed = actor.isDisplayed;
-      if (isDisplayed !== actor.wasDisplayed) {
-        changes.push(actor);
-        // Updating the original value
-        actor.wasDisplayed = isDisplayed;
-      }
-    }
-
-    if (changes.length) {
-      this.emit("display-change", changes);
-    }
-  },
-
-  /**
-   * When the browser window gets resized, relay the event to the front.
-   */
-  _onResize: function () {
-    this.emit("resize");
-  },
-
-  /**
-   * This is kept for backward-compatibility reasons with older remote targets.
-   * Targets prior to bug 916443.
-   *
-   * pick/cancelPick are used to pick a node on click on the content
-   * document. But in their implementation prior to bug 916443, they don't allow
-   * highlighting on hover.
-   * The client-side now uses the highlighter actor's pick and cancelPick
-   * methods instead. The client-side uses the the highlightable trait found in
-   * the root actor to determine which version of pick to use.
-   *
-   * As for highlight, the new highlighter actor is used instead of the walker's
-   * highlight method. Same here though, the client-side uses the highlightable
-   * trait to dertermine which to use.
-   *
-   * Keeping these actor methods for now allows newer client-side debuggers to
-   * inspect fxos 1.2 remote targets or older firefox desktop remote targets.
-   */
-  pick: function () {},
-  cancelPick: function () {},
-  highlight: function (node) {},
-
-  /**
-   * Ensures that the node is attached and it can be accessed from the root.
-   *
-   * @param {(Node|NodeActor)} nodes The nodes
-   * @return {Object} An object compatible with the disconnectedNode type.
-   */
-  attachElement: function (node) {
-    let { nodes, newParents } = this.attachElements([node]);
-    return {
-      node: nodes[0],
-      newParents: newParents
-    };
-  },
-
-  /**
-   * Ensures that the nodes are attached and they can be accessed from the root.
-   *
-   * @param {(Node[]|NodeActor[])} nodes The nodes
-   * @return {Object} An object compatible with the disconnectedNodeArray type.
-   */
-  attachElements: function (nodes) {
-    let nodeActors = [];
-    let newParents = new Set();
-    for (let node of nodes) {
-      if (!(node instanceof NodeActor)) {
-        // If an anonymous node was passed in and we aren't supposed to know
-        // about it, then consult with the document walker as the source of
-        // truth about which elements exist.
-        if (!this.showAllAnonymousContent && isAnonymous(node)) {
-          node = this.getDocumentWalker(node).currentNode;
-        }
-
-        node = this._ref(node);
-      }
-
-      this.ensurePathToRoot(node, newParents);
-      // If nodes may be an array of raw nodes, we're sure to only have
-      // NodeActors with the following array.
-      nodeActors.push(node);
-    }
-
-    return {
-      nodes: nodeActors,
-      newParents: [...newParents]
-    };
-  },
-
-  /**
-   * Return the document node that contains the given node,
-   * or the root node if no node is specified.
-   * @param NodeActor node
-   *        The node whose document is needed, or null to
-   *        return the root.
-   */
-  document: function (node) {
-    let doc = isNodeDead(node) ? this.rootDoc : nodeDocument(node.rawNode);
-    return this._ref(doc);
-  },
-
-  /**
-   * Return the documentElement for the document containing the
-   * given node.
-   * @param NodeActor node
-   *        The node whose documentElement is requested, or null
-   *        to use the root document.
-   */
-  documentElement: function (node) {
-    let elt = isNodeDead(node)
-              ? this.rootDoc.documentElement
-              : nodeDocument(node.rawNode).documentElement;
-    return this._ref(elt);
-  },
-
-  /**
-   * Return all parents of the given node, ordered from immediate parent
-   * to root.
-   * @param NodeActor node
-   *    The node whose parents are requested.
-   * @param object options
-   *    Named options, including:
-   *    `sameDocument`: If true, parents will be restricted to the same
-   *      document as the node.
-   *    `sameTypeRootTreeItem`: If true, this will not traverse across
-   *     different types of docshells.
-   */
-  parents: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return [];
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let parents = [];
-    let cur;
-    while ((cur = walker.parentNode())) {
-      if (options.sameDocument &&
-          nodeDocument(cur) != nodeDocument(node.rawNode)) {
-        break;
-      }
-
-      if (options.sameTypeRootTreeItem &&
-          nodeDocshell(cur).sameTypeRootTreeItem !=
-          nodeDocshell(node.rawNode).sameTypeRootTreeItem) {
-        break;
-      }
-
-      parents.push(this._ref(cur));
-    }
-    return parents;
-  },
-
-  parentNode: function (node) {
-    let walker = this.getDocumentWalker(node.rawNode);
-    let parent = walker.parentNode();
-    if (parent) {
-      return this._ref(parent);
-    }
-    return null;
-  },
-
-  /**
-   * If the given NodeActor only has a single text node as a child with a text
-   * content small enough to be inlined, return that child's NodeActor.
-   *
-   * @param NodeActor node
-   */
-  inlineTextChild: function (node) {
-    // Quick checks to prevent creating a new walker if possible.
-    if (node.isBeforePseudoElement ||
-        node.isAfterPseudoElement ||
-        node.rawNode.nodeType != Ci.nsIDOMNode.ELEMENT_NODE ||
-        node.rawNode.children.length > 0) {
-      return undefined;
-    }
-
-    let docWalker = this.getDocumentWalker(node.rawNode);
-    let firstChild = docWalker.firstChild();
-
-    // Bail out if:
-    // - more than one child
-    // - unique child is not a text node
-    // - unique child is a text node, but is too long to be inlined
-    if (!firstChild ||
-        docWalker.nextSibling() ||
-        firstChild.nodeType !== Ci.nsIDOMNode.TEXT_NODE ||
-        firstChild.nodeValue.length > gValueSummaryLength
-        ) {
-      return undefined;
-    }
-
-    return this._ref(firstChild);
-  },
-
-  /**
-   * Mark a node as 'retained'.
-   *
-   * A retained node is not released when `releaseNode` is called on its
-   * parent, or when a parent is released with the `cleanup` option to
-   * `getMutations`.
-   *
-   * When a retained node's parent is released, a retained mode is added to
-   * the walker's "retained orphans" list.
-   *
-   * Retained nodes can be deleted by providing the `force` option to
-   * `releaseNode`.  They will also be released when their document
-   * has been destroyed.
-   *
-   * Retaining a node makes no promise about its children;  They can
-   * still be removed by normal means.
-   */
-  retainNode: function (node) {
-    node.retained = true;
-  },
-
-  /**
-   * Remove the 'retained' mark from a node.  If the node was a
-   * retained orphan, release it.
-   */
-  unretainNode: function (node) {
-    node.retained = false;
-    if (this._retainedOrphans.has(node)) {
-      this._retainedOrphans.delete(node);
-      this.releaseNode(node);
-    }
-  },
-
-  /**
-   * Release actors for a node and all child nodes.
-   */
-  releaseNode: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    if (node.retained && !options.force) {
-      this._retainedOrphans.add(node);
-      return;
-    }
-
-    if (node.retained) {
-      // Forcing a retained node to go away.
-      this._retainedOrphans.delete(node);
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-
-    let child = walker.firstChild();
-    while (child) {
-      let childActor = this.getNode(child);
-      if (childActor) {
-        this.releaseNode(childActor, options);
-      }
-      child = walker.nextSibling();
-    }
-
-    node.destroy();
-  },
-
-  /**
-   * Add any nodes between `node` and the walker's root node that have not
-   * yet been seen by the client.
-   */
-  ensurePathToRoot: function (node, newParents = new Set()) {
-    if (!node) {
-      return newParents;
-    }
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let parent = this.getNode(cur);
-      if (!parent) {
-        // This parent didn't exist, so hasn't been seen by the client yet.
-        newParents.add(this._ref(cur));
-      } else {
-        // This parent did exist, so the client knows about it.
-        return newParents;
-      }
-    }
-    return newParents;
-  },
-
-  /**
-   * Return children of the given node.  By default this method will return
-   * all children of the node, but there are options that can restrict this
-   * to a more manageable subset.
-   *
-   * @param NodeActor node
-   *    The node whose children you're curious about.
-   * @param object options
-   *    Named options:
-   *    `maxNodes`: The set of nodes returned by the method will be no longer
-   *       than maxNodes.
-   *    `start`: If a node is specified, the list of nodes will start
-   *       with the given child.  Mutally exclusive with `center`.
-   *    `center`: If a node is specified, the given node will be as centered
-   *       as possible in the list, given how close to the ends of the child
-   *       list it is.  Mutually exclusive with `start`.
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   *
-   * @returns an object with three items:
-   *    hasFirst: true if the first child of the node is included in the list.
-   *    hasLast: true if the last child of the node is included in the list.
-   *    nodes: Child nodes returned by the request.
-   */
-  children: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    if (options.center && options.start) {
-      throw Error("Can't specify both 'center' and 'start' options.");
-    }
-    let maxNodes = options.maxNodes || -1;
-    if (maxNodes == -1) {
-      maxNodes = Number.MAX_VALUE;
-    }
-
-    // We're going to create a few document walkers with the same filter,
-    // make it easier.
-    let getFilteredWalker = documentWalkerNode => {
-      let { whatToShow } = options;
-      // Use SKIP_TO_SIBLING to force the walker to use a sibling of the provided node
-      // in case this one is incompatible with the walker's filter function.
-      return this.getDocumentWalker(documentWalkerNode, whatToShow, SKIP_TO_SIBLING);
-    };
-
-    // Need to know the first and last child.
-    let rawNode = node.rawNode;
-    let firstChild = getFilteredWalker(rawNode).firstChild();
-    let lastChild = getFilteredWalker(rawNode).lastChild();
-
-    if (!firstChild) {
-      // No children, we're done.
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    let start;
-    if (options.center) {
-      start = options.center.rawNode;
-    } else if (options.start) {
-      start = options.start.rawNode;
-    } else {
-      start = firstChild;
-    }
-
-    let nodes = [];
-
-    // Start by reading backward from the starting point if we're centering...
-    let backwardWalker = getFilteredWalker(start);
-    if (backwardWalker.currentNode != firstChild && options.center) {
-      backwardWalker.previousSibling();
-      let backwardCount = Math.floor(maxNodes / 2);
-      let backwardNodes = this._readBackward(backwardWalker, backwardCount);
-      nodes = backwardNodes;
-    }
-
-    // Then read forward by any slack left in the max children...
-    let forwardWalker = getFilteredWalker(start);
-    let forwardCount = maxNodes - nodes.length;
-    nodes = nodes.concat(this._readForward(forwardWalker, forwardCount));
-
-    // If there's any room left, it means we've run all the way to the end.
-    // If we're centering, check if there are more items to read at the front.
-    let remaining = maxNodes - nodes.length;
-    if (options.center && remaining > 0 && nodes[0].rawNode != firstChild) {
-      let firstNodes = this._readBackward(backwardWalker, remaining);
-
-      // Then put it all back together.
-      nodes = firstNodes.concat(nodes);
-    }
-
-    return {
-      hasFirst: nodes[0].rawNode == firstChild,
-      hasLast: nodes[nodes.length - 1].rawNode == lastChild,
-      nodes: nodes
-    };
-  },
-
-  /**
-   * Return siblings of the given node.  By default this method will return
-   * all siblings of the node, but there are options that can restrict this
-   * to a more manageable subset.
-   *
-   * If `start` or `center` are not specified, this method will center on the
-   * node whose siblings are requested.
-   *
-   * @param NodeActor node
-   *    The node whose children you're curious about.
-   * @param object options
-   *    Named options:
-   *    `maxNodes`: The set of nodes returned by the method will be no longer
-   *       than maxNodes.
-   *    `start`: If a node is specified, the list of nodes will start
-   *       with the given child.  Mutally exclusive with `center`.
-   *    `center`: If a node is specified, the given node will be as centered
-   *       as possible in the list, given how close to the ends of the child
-   *       list it is.  Mutually exclusive with `start`.
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   *
-   * @returns an object with three items:
-   *    hasFirst: true if the first child of the node is included in the list.
-   *    hasLast: true if the last child of the node is included in the list.
-   *    nodes: Child nodes returned by the request.
-   */
-  siblings: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return { hasFirst: true, hasLast: true, nodes: [] };
-    }
-
-    let parentNode = this.getDocumentWalker(node.rawNode, options.whatToShow)
-                         .parentNode();
-    if (!parentNode) {
-      return {
-        hasFirst: true,
-        hasLast: true,
-        nodes: [node]
-      };
-    }
-
-    if (!(options.start || options.center)) {
-      options.center = node;
-    }
-
-    return this.children(this._ref(parentNode), options);
-  },
-
-  /**
-   * Get the next sibling of a given node.  Getting nodes one at a time
-   * might be inefficient, be careful.
-   *
-   * @param object options
-   *    Named options:
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   */
-  nextSibling: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode, options.whatToShow);
-    let sibling = walker.nextSibling();
-    return sibling ? this._ref(sibling) : null;
-  },
-
-  /**
-   * Get the previous sibling of a given node.  Getting nodes one at a time
-   * might be inefficient, be careful.
-   *
-   * @param object options
-   *    Named options:
-   *    `whatToShow`: A bitmask of node types that should be included.  See
-   *       https://developer.mozilla.org/en-US/docs/Web/API/NodeFilter.
-   */
-  previousSibling: function (node, options = {}) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode, options.whatToShow);
-    let sibling = walker.previousSibling();
-    return sibling ? this._ref(sibling) : null;
-  },
-
-  /**
-   * Helper function for the `children` method: Read forward in the sibling
-   * list into an array with `count` items, including the current node.
-   */
-  _readForward: function (walker, count) {
-    let ret = [];
-
-    let node = walker.currentNode;
-    do {
-      if (!walker.isSkippedNode(node)) {
-        // The walker can be on a node that would be filtered out if it didn't find any
-        // other node to fallback to.
-        ret.push(this._ref(node));
-      }
-      node = walker.nextSibling();
-    } while (node && --count);
-    return ret;
-  },
-
-  /**
-   * Helper function for the `children` method: Read backward in the sibling
-   * list into an array with `count` items, including the current node.
-   */
-  _readBackward: function (walker, count) {
-    let ret = [];
-
-    let node = walker.currentNode;
-    do {
-      if (!walker.isSkippedNode(node)) {
-        // The walker can be on a node that would be filtered out if it didn't find any
-        // other node to fallback to.
-        ret.push(this._ref(node));
-      }
-      node = walker.previousSibling();
-    } while (node && --count);
-    ret.reverse();
-    return ret;
-  },
-
-  /**
-   * Return the first node in the document that matches the given selector.
-   * See https://developer.mozilla.org/en-US/docs/Web/API/Element.querySelector
-   *
-   * @param NodeActor baseNode
-   * @param string selector
-   */
-  querySelector: function (baseNode, selector) {
-    if (isNodeDead(baseNode)) {
-      return {};
-    }
-
-    let node = baseNode.rawNode.querySelector(selector);
-    if (!node) {
-      return {};
-    }
-
-    return this.attachElement(node);
-  },
-
-  /**
-   * Return a NodeListActor with all nodes that match the given selector.
-   * See https://developer.mozilla.org/en-US/docs/Web/API/Element.querySelectorAll
-   *
-   * @param NodeActor baseNode
-   * @param string selector
-   */
-  querySelectorAll: function (baseNode, selector) {
-    let nodeList = null;
-
-    try {
-      nodeList = baseNode.rawNode.querySelectorAll(selector);
-    } catch (e) {
-      // Bad selector. Do nothing as the selector can come from a searchbox.
-    }
-
-    return new NodeListActor(this, nodeList);
-  },
-
-  /**
-   * Get a list of nodes that match the given selector in all known frames of
-   * the current content page.
-   * @param {String} selector.
-   * @return {Array}
-   */
-  _multiFrameQuerySelectorAll: function (selector) {
-    let nodes = [];
-
-    for (let {document} of this.tabActor.windows) {
-      try {
-        nodes = [...nodes, ...document.querySelectorAll(selector)];
-      } catch (e) {
-        // Bad selector. Do nothing as the selector can come from a searchbox.
-      }
-    }
-
-    return nodes;
-  },
-
-  /**
-   * Return a NodeListActor with all nodes that match the given selector in all
-   * frames of the current content page.
-   * @param {String} selector
-   */
-  multiFrameQuerySelectorAll: function (selector) {
-    return new NodeListActor(this, this._multiFrameQuerySelectorAll(selector));
-  },
-
-  /**
-   * Search the document for a given string.
-   * Results will be searched with the walker-search module (searches through
-   * tag names, attribute names and values, and text contents).
-   *
-   * @returns {searchresult}
-   *            - {NodeList} list
-   *            - {Array<Object>} metadata. Extra information with indices that
-   *                              match up with node list.
-   */
-  search: function (query) {
-    let results = this.walkerSearch.search(query);
-    let nodeList = new NodeListActor(this, results.map(r => r.node));
-
-    return {
-      list: nodeList,
-      metadata: []
-    };
-  },
-
-  /**
-   * Returns a list of matching results for CSS selector autocompletion.
-   *
-   * @param string query
-   *        The selector query being completed
-   * @param string completing
-   *        The exact token being completed out of the query
-   * @param string selectorState
-   *        One of "pseudo", "id", "tag", "class", "null"
-   */
-  getSuggestionsForQuery: function (query, completing, selectorState) {
-    let sugs = {
-      classes: new Map(),
-      tags: new Map(),
-      ids: new Map()
-    };
-    let result = [];
-    let nodes = null;
-    // Filtering and sorting the results so that protocol transfer is miminal.
-    switch (selectorState) {
-      case "pseudo":
-        result = PSEUDO_SELECTORS.filter(item => {
-          return item[0].startsWith(":" + completing);
-        });
-        break;
-
-      case "class":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("[class]");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          for (let className of node.classList) {
-            sugs.classes.set(className, (sugs.classes.get(className)|0) + 1);
-          }
-        }
-        sugs.classes.delete("");
-        sugs.classes.delete(HIDDEN_CLASS);
-        for (let [className, count] of sugs.classes) {
-          if (className.startsWith(completing)) {
-            result.push(["." + CSS.escape(className), count, selectorState]);
-          }
-        }
-        break;
-
-      case "id":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("[id]");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          sugs.ids.set(node.id, (sugs.ids.get(node.id)|0) + 1);
-        }
-        for (let [id, count] of sugs.ids) {
-          if (id.startsWith(completing) && id !== "") {
-            result.push(["#" + CSS.escape(id), count, selectorState]);
-          }
-        }
-        break;
-
-      case "tag":
-        if (!query) {
-          nodes = this._multiFrameQuerySelectorAll("*");
-        } else {
-          nodes = this._multiFrameQuerySelectorAll(query);
-        }
-        for (let node of nodes) {
-          let tag = node.localName;
-          sugs.tags.set(tag, (sugs.tags.get(tag)|0) + 1);
-        }
-        for (let [tag, count] of sugs.tags) {
-          if ((new RegExp("^" + completing + ".*", "i")).test(tag)) {
-            result.push([tag, count, selectorState]);
-          }
-        }
-
-        // For state 'tag' (no preceding # or .) and when there's no query (i.e.
-        // only one word) then search for the matching classes and ids
-        if (!query) {
-          result = [
-            ...result,
-            ...this.getSuggestionsForQuery(null, completing, "class")
-                   .suggestions,
-            ...this.getSuggestionsForQuery(null, completing, "id")
-                   .suggestions
-          ];
-        }
-
-        break;
-
-      case "null":
-        nodes = this._multiFrameQuerySelectorAll(query);
-        for (let node of nodes) {
-          sugs.ids.set(node.id, (sugs.ids.get(node.id)|0) + 1);
-          let tag = node.localName;
-          sugs.tags.set(tag, (sugs.tags.get(tag)|0) + 1);
-          for (let className of node.classList) {
-            sugs.classes.set(className, (sugs.classes.get(className)|0) + 1);
-          }
-        }
-        for (let [tag, count] of sugs.tags) {
-          tag && result.push([tag, count]);
-        }
-        for (let [id, count] of sugs.ids) {
-          id && result.push(["#" + id, count]);
-        }
-        sugs.classes.delete("");
-        sugs.classes.delete(HIDDEN_CLASS);
-        for (let [className, count] of sugs.classes) {
-          className && result.push(["." + className, count]);
-        }
-    }
-
-    // Sort by count (desc) and name (asc)
-    result = result.sort((a, b) => {
-      // Computed a sortable string with first the inverted count, then the name
-      let sortA = (10000 - a[1]) + a[0];
-      let sortB = (10000 - b[1]) + b[0];
-
-      // Prefixing ids, classes and tags, to group results
-      let firstA = a[0].substring(0, 1);
-      let firstB = b[0].substring(0, 1);
-
-      if (firstA === "#") {
-        sortA = "2" + sortA;
-      } else if (firstA === ".") {
-        sortA = "1" + sortA;
-      } else {
-        sortA = "0" + sortA;
-      }
-
-      if (firstB === "#") {
-        sortB = "2" + sortB;
-      } else if (firstB === ".") {
-        sortB = "1" + sortB;
-      } else {
-        sortB = "0" + sortB;
-      }
-
-      // String compare
-      return sortA.localeCompare(sortB);
-    });
-
-    result.slice(0, 25);
-
-    return {
-      query: query,
-      suggestions: result
-    };
-  },
-
-  /**
-   * Add a pseudo-class lock to a node.
-   *
-   * @param NodeActor node
-   * @param string pseudo
-   *    A pseudoclass: ':hover', ':active', ':focus'
-   * @param options
-   *    Options object:
-   *    `parents`: True if the pseudo-class should be added
-   *      to parent nodes.
-   *    `enabled`: False if the pseudo-class should be locked
-   *      to 'off'. Defaults to true.
-   *
-   * @returns An empty packet.  A "pseudoClassLock" mutation will
-   *    be queued for any changed nodes.
-   */
-  addPseudoClassLock: function (node, pseudo, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    // There can be only one node locked per pseudo, so dismiss all existing
-    // ones
-    for (let locked of this._activePseudoClassLocks) {
-      if (InspectorUtils.hasPseudoClassLock(locked.rawNode, pseudo)) {
-        this._removePseudoClassLock(locked, pseudo);
-      }
-    }
-
-    let enabled = options.enabled === undefined ||
-                  options.enabled;
-    this._addPseudoClassLock(node, pseudo, enabled);
-
-    if (!options.parents) {
-      return;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let curNode = this._ref(cur);
-      this._addPseudoClassLock(curNode, pseudo, enabled);
-    }
-  },
-
-  _queuePseudoClassMutation: function (node) {
-    this.queueMutation({
-      target: node.actorID,
-      type: "pseudoClassLock",
-      pseudoClassLocks: node.writePseudoClassLocks()
-    });
-  },
-
-  _addPseudoClassLock: function (node, pseudo, enabled) {
-    if (node.rawNode.nodeType !== Ci.nsIDOMNode.ELEMENT_NODE) {
-      return false;
-    }
-    InspectorUtils.addPseudoClassLock(node.rawNode, pseudo, enabled);
-    this._activePseudoClassLocks.add(node);
-    this._queuePseudoClassMutation(node);
-    return true;
-  },
-
-  hideNode: function (node) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    loadSheet(node.rawNode.ownerGlobal, HELPER_SHEET);
-    node.rawNode.classList.add(HIDDEN_CLASS);
-  },
-
-  unhideNode: function (node) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    node.rawNode.classList.remove(HIDDEN_CLASS);
-  },
-
-  /**
-   * Remove a pseudo-class lock from a node.
-   *
-   * @param NodeActor node
-   * @param string pseudo
-   *    A pseudoclass: ':hover', ':active', ':focus'
-   * @param options
-   *    Options object:
-   *    `parents`: True if the pseudo-class should be removed
-   *      from parent nodes.
-   *
-   * @returns An empty response.  "pseudoClassLock" mutations
-   *    will be emitted for any changed nodes.
-   */
-  removePseudoClassLock: function (node, pseudo, options = {}) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    this._removePseudoClassLock(node, pseudo);
-
-    // Remove pseudo class for children as we don't want to allow
-    // turning it on for some childs without setting it on some parents
-    for (let locked of this._activePseudoClassLocks) {
-      if (node.rawNode.contains(locked.rawNode) &&
-          InspectorUtils.hasPseudoClassLock(locked.rawNode, pseudo)) {
-        this._removePseudoClassLock(locked, pseudo);
-      }
-    }
-
-    if (!options.parents) {
-      return;
-    }
-
-    let walker = this.getDocumentWalker(node.rawNode);
-    let cur;
-    while ((cur = walker.parentNode())) {
-      let curNode = this._ref(cur);
-      this._removePseudoClassLock(curNode, pseudo);
-    }
-  },
-
-  _removePseudoClassLock: function (node, pseudo) {
-    if (node.rawNode.nodeType != Ci.nsIDOMNode.ELEMENT_NODE) {
-      return false;
-    }
-    InspectorUtils.removePseudoClassLock(node.rawNode, pseudo);
-    if (!node.writePseudoClassLocks()) {
-      this._activePseudoClassLocks.delete(node);
-    }
-
-    this._queuePseudoClassMutation(node);
-    return true;
-  },
-
-  /**
-   * Clear all the pseudo-classes on a given node or all nodes.
-   * @param {NodeActor} node Optional node to clear pseudo-classes on
-   */
-  clearPseudoClassLocks: function (node) {
-    if (node && isNodeDead(node)) {
-      return;
-    }
-
-    if (node) {
-      InspectorUtils.clearPseudoClassLocks(node.rawNode);
-      this._activePseudoClassLocks.delete(node);
-      this._queuePseudoClassMutation(node);
-    } else {
-      for (let locked of this._activePseudoClassLocks) {
-        InspectorUtils.clearPseudoClassLocks(locked.rawNode);
-        this._activePseudoClassLocks.delete(locked);
-        this._queuePseudoClassMutation(locked);
-      }
-    }
-  },
-
-  /**
-   * Get a node's innerHTML property.
-   */
-  innerHTML: function (node) {
-    let html = "";
-    if (!isNodeDead(node)) {
-      html = node.rawNode.innerHTML;
-    }
-    return LongStringActor(this.conn, html);
-  },
-
-  /**
-   * Set a node's innerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   * @param {string} value The piece of HTML content.
-   */
-  setInnerHTML: function (node, value) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    let rawNode = node.rawNode;
-    if (rawNode.nodeType !== rawNode.ownerDocument.ELEMENT_NODE) {
-      throw new Error("Can only change innerHTML to element nodes");
-    }
-    // eslint-disable-next-line no-unsanitized/property
-    rawNode.innerHTML = value;
-  },
-
-  /**
-   * Get a node's outerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   */
-  outerHTML: function (node) {
-    let outerHTML = "";
-    if (!isNodeDead(node)) {
-      outerHTML = node.rawNode.outerHTML;
-    }
-    return LongStringActor(this.conn, outerHTML);
-  },
-
-  /**
-   * Set a node's outerHTML property.
-   *
-   * @param {NodeActor} node The node.
-   * @param {string} value The piece of HTML content.
-   */
-  setOuterHTML: function (node, value) {
-    if (isNodeDead(node)) {
-      return;
-    }
-
-    let parsedDOM = DOMParser.parseFromString(value, "text/html");
-    let rawNode = node.rawNode;
-    let parentNode = rawNode.parentNode;
-
-    // Special case for head and body.  Setting document.body.outerHTML
-    // creates an extra <head> tag, and document.head.outerHTML creates
-    // an extra <body>.  So instead we will call replaceChild with the
-    // parsed DOM, assuming that they aren't trying to set both tags at once.
-    if (rawNode.tagName === "BODY") {
-      if (parsedDOM.head.innerHTML === "") {
-        parentNode.replaceChild(parsedDOM.body, rawNode);
-      } else {
-      // eslint-disable-next-line no-unsanitized/property
-        rawNode.outerHTML = value;
-      }
-    } else if (rawNode.tagName === "HEAD") {
-      if (parsedDOM.body.innerHTML === "") {
-        parentNode.replaceChild(parsedDOM.head, rawNode);
-      } else {
-        // eslint-disable-next-line no-unsanitized/property
-        rawNode.outerHTML = value;
-      }
-    } else if (node.isDocumentElement()) {
-      // Unable to set outerHTML on the document element.  Fall back by
-      // setting attributes manually, then replace the body and head elements.
-      let finalAttributeModifications = [];
-      let attributeModifications = {};
-      for (let attribute of rawNode.attributes) {
-        attributeModifications[attribute.name] = null;
-      }
-      for (let attribute of parsedDOM.documentElement.attributes) {
-        attributeModifications[attribute.name] = attribute.value;
-      }
-      for (let key in attributeModifications) {
-        finalAttributeModifications.push({
-          attributeName: key,
-          newValue: attributeModifications[key]
-        });
-      }
-      node.modifyAttributes(finalAttributeModifications);
-      rawNode.replaceChild(parsedDOM.head, rawNode.querySelector("head"));
-      rawNode.replaceChild(parsedDOM.body, rawNode.querySelector("body"));
-    } else {
-      // eslint-disable-next-line no-unsanitized/property
-      rawNode.outerHTML = value;
-    }
-  },
-
-  /**
-   * Insert adjacent HTML to a node.
-   *
-   * @param {Node} node
-   * @param {string} position One of "beforeBegin", "afterBegin", "beforeEnd",
-   *                          "afterEnd" (see Element.insertAdjacentHTML).
-   * @param {string} value The HTML content.
-   */
-  insertAdjacentHTML: function (node, position, value) {
-    if (isNodeDead(node)) {
-      return {node: [], newParents: []};
-    }
-
-    let rawNode = node.rawNode;
-    let isInsertAsSibling = position === "beforeBegin" ||
-      position === "afterEnd";
-
-    // Don't insert anything adjacent to the document element.
-    if (isInsertAsSibling && node.isDocumentElement()) {
-      throw new Error("Can't insert adjacent element to the root.");
-    }
-
-    let rawParentNode = rawNode.parentNode;
-    if (!rawParentNode && isInsertAsSibling) {
-      throw new Error("Can't insert as sibling without parent node.");
-    }
-
-    // We can't use insertAdjacentHTML, because we want to return the nodes
-    // being created (so the front can remove them if the user undoes
-    // the change). So instead, use Range.createContextualFragment().
-    let range = rawNode.ownerDocument.createRange();
-    if (position === "beforeBegin" || position === "afterEnd") {
-      range.selectNode(rawNode);
-    } else {
-      range.selectNodeContents(rawNode);
-    }
-    let docFrag = range.createContextualFragment(value);
-    let newRawNodes = Array.from(docFrag.childNodes);
-    switch (position) {
-      case "beforeBegin":
-        rawParentNode.insertBefore(docFrag, rawNode);
-        break;
-      case "afterEnd":
-        // Note: if the second argument is null, rawParentNode.insertBefore
-        // behaves like rawParentNode.appendChild.
-        rawParentNode.insertBefore(docFrag, rawNode.nextSibling);
-        break;
-      case "afterBegin":
-        rawNode.insertBefore(docFrag, rawNode.firstChild);
-        break;
-      case "beforeEnd":
-        rawNode.appendChild(docFrag);
-        break;
-      default:
-        throw new Error("Invalid position value. Must be either " +
-          "'beforeBegin', 'beforeEnd', 'afterBegin' or 'afterEnd'.");
-    }
-
-    return this.attachElements(newRawNodes);
-  },
-
-  /**
-   * Duplicate a specified node
-   *
-   * @param {NodeActor} node The node to duplicate.
-   */
-  duplicateNode: function ({rawNode}) {
-    let clonedNode = rawNode.cloneNode(true);
-    rawNode.parentNode.insertBefore(clonedNode, rawNode.nextSibling);
-  },
-
-  /**
-   * Test whether a node is a document or a document element.
-   *
-   * @param {NodeActor} node The node to remove.
-   * @return {boolean} True if the node is a document or a document element.
-   */
-  isDocumentOrDocumentElementNode: function (node) {
-    return ((node.rawNode.ownerDocument &&
-      node.rawNode.ownerDocument.documentElement === this.rawNode) ||
-      node.rawNode.nodeType === Ci.nsIDOMNode.DOCUMENT_NODE);
-  },
-
-  /**
-   * Removes a node from its parent node.
-   *
-   * @param {NodeActor} node The node to remove.
-   * @returns The node's nextSibling before it was removed.
-   */
-  removeNode: function (node) {
-    if (isNodeDead(node) || this.isDocumentOrDocumentElementNode(node)) {
-      throw Error("Cannot remove document, document elements or dead nodes.");
-    }
-
-    let nextSibling = this.nextSibling(node);
-    node.rawNode.remove();
-    // Mutation events will take care of the rest.
-    return nextSibling;
-  },
-
-  /**
-   * Removes an array of nodes from their parent node.
-   *
-   * @param {NodeActor[]} nodes The nodes to remove.
-   */
-  removeNodes: function (nodes) {
-    // Check that all nodes are valid before processing the removals.
-    for (let node of nodes) {
-      if (isNodeDead(node) || this.isDocumentOrDocumentElementNode(node)) {
-        throw Error("Cannot remove document, document elements or dead nodes");
-      }
-    }
-
-    for (let node of nodes) {
-      node.rawNode.remove();
-      // Mutation events will take care of the rest.
-    }
-  },
-
-  /**
-   * Insert a node into the DOM.
-   */
-  insertBefore: function (node, parent, sibling) {
-    if (isNodeDead(node) ||
-        isNodeDead(parent) ||
-        (sibling && isNodeDead(sibling))) {
-      return;
-    }
-
-    let rawNode = node.rawNode;
-    let rawParent = parent.rawNode;
-    let rawSibling = sibling ? sibling.rawNode : null;
-
-    // Don't bother inserting a node if the document position isn't going
-    // to change. This prevents needless iframes reloading and mutations.
-    if (rawNode.parentNode === rawParent) {
-      let currentNextSibling = this.nextSibling(node);
-      currentNextSibling = currentNextSibling ? currentNextSibling.rawNode :
-                                                null;
-
-      if (rawNode === rawSibling || currentNextSibling === rawSibling) {
-        return;
-      }
-    }
-
-    rawParent.insertBefore(rawNode, rawSibling);
-  },
-
-  /**
-   * Editing a node's tagname actually means creating a new node with the same
-   * attributes, removing the node and inserting the new one instead.
-   * This method does not return anything as mutation events are taking care of
-   * informing the consumers about changes.
-   */
-  editTagName: function (node, tagName) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let oldNode = node.rawNode;
-
-    // Create a new element with the same attributes as the current element and
-    // prepare to replace the current node with it.
-    let newNode;
-    try {
-      newNode = nodeDocument(oldNode).createElement(tagName);
-    } catch (x) {
-      // Failed to create a new element with that tag name, ignore the change,
-      // and signal the error to the front.
-      return Promise.reject(new Error("Could not change node's tagName to " + tagName));
-    }
-
-    let attrs = oldNode.attributes;
-    for (let i = 0; i < attrs.length; i++) {
-      newNode.setAttribute(attrs[i].name, attrs[i].value);
-    }
-
-    // Insert the new node, and transfer the old node's children.
-    oldNode.parentNode.insertBefore(newNode, oldNode);
-    while (oldNode.firstChild) {
-      newNode.appendChild(oldNode.firstChild);
-    }
-
-    oldNode.remove();
-    return null;
-  },
-
-  /**
-   * Get any pending mutation records.  Must be called by the client after
-   * the `new-mutations` notification is received.  Returns an array of
-   * mutation records.
-   *
-   * Mutation records have a basic structure:
-   *
-   * {
-   *   type: attributes|characterData|childList,
-   *   target: <domnode actor ID>,
-   * }
-   *
-   * And additional attributes based on the mutation type:
-   *
-   * `attributes` type:
-   *   attributeName: <string> - the attribute that changed
-   *   attributeNamespace: <string> - the attribute's namespace URI, if any.
-   *   newValue: <string> - The new value of the attribute, if any.
-   *
-   * `characterData` type:
-   *   newValue: <string> - the new nodeValue for the node
-   *
-   * `childList` type is returned when the set of children for a node
-   * has changed.  Includes extra data, which can be used by the client to
-   * maintain its ownership subtree.
-   *
-   *   added: array of <domnode actor ID> - The list of actors *previously
-   *     seen by the client* that were added to the target node.
-   *   removed: array of <domnode actor ID> The list of actors *previously
-   *     seen by the client* that were removed from the target node.
-   *   inlineTextChild: If the node now has a single text child, it will
-   *     be sent here.
-   *
-   * Actors that are included in a MutationRecord's `removed` but
-   * not in an `added` have been removed from the client's ownership
-   * tree (either by being moved under a node the client has seen yet
-   * or by being removed from the tree entirely), and is considered
-   * 'orphaned'.
-   *
-   * Keep in mind that if a node that the client hasn't seen is moved
-   * into or out of the target node, it will not be included in the
-   * removedNodes and addedNodes list, so if the client is interested
-   * in the new set of children it needs to issue a `children` request.
-   */
-  getMutations: function (options = {}) {
-    let pending = this._pendingMutations || [];
-    this._pendingMutations = [];
-    this._waitingForGetMutations = false;
-
-    if (options.cleanup) {
-      for (let node of this._orphaned) {
-        // Release the orphaned node.  Nodes or children that have been
-        // retained will be moved to this._retainedOrphans.
-        this.releaseNode(node);
-      }
-      this._orphaned = new Set();
-    }
-
-    return pending;
-  },
-
-  queueMutation: function (mutation) {
-    if (!this.actorID || this._destroyed) {
-      // We've been destroyed, don't bother queueing this mutation.
-      return;
-    }
-
-    // Add the mutation to the list of mutations to be retrieved next.
-    this._pendingMutations.push(mutation);
-
-    // Bail out if we already emitted a new-mutations event and are waiting for a client
-    // to retrieve them.
-    if (this._waitingForGetMutations) {
-      return;
-    }
-
-    if (IMMEDIATE_MUTATIONS.includes(mutation.type)) {
-      this._emitNewMutations();
-    } else {
-      /**
-       * If many mutations are fired at the same time, clients might sequentially request
-       * children/siblings for updated nodes, which can be costly. By throttling the calls
-       * to getMutations, duplicated mutations will be ignored.
-       */
-      this._throttledEmitNewMutations();
-    }
-  },
-
-  _emitNewMutations: function () {
-    if (!this.actorID || this._destroyed) {
-      // Bail out if the actor was destroyed after throttling this call.
-      return;
-    }
-
-    if (this._waitingForGetMutations || this._pendingMutations.length == 0) {
-      // Bail out if we already fired the new-mutation event or if no mutations are
-      // waiting to be retrieved.
-      return;
-    }
-
-    this._waitingForGetMutations = true;
-    this.emit("new-mutations");
-  },
-
-  /**
-   * Handles mutations from the DOM mutation observer API.
-   *
-   * @param array[MutationRecord] mutations
-   *    See https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver#MutationRecord
-   */
-  onMutations: function (mutations) {
-    // Notify any observers that want *all* mutations (even on nodes that aren't
-    // referenced).  This is not sent over the protocol so can only be used by
-    // scripts running in the server process.
-    this.emit("any-mutation");
-
-    for (let change of mutations) {
-      let targetActor = this.getNode(change.target);
-      if (!targetActor) {
-        continue;
-      }
-      let targetNode = change.target;
-      let type = change.type;
-      let mutation = {
-        type: type,
-        target: targetActor.actorID,
-      };
-
-      if (type === "attributes") {
-        mutation.attributeName = change.attributeName;
-        mutation.attributeNamespace = change.attributeNamespace || undefined;
-        mutation.newValue = targetNode.hasAttribute(mutation.attributeName) ?
-                            targetNode.getAttribute(mutation.attributeName)
-                            : null;
-      } else if (type === "characterData") {
-        mutation.newValue = targetNode.nodeValue;
-        this._maybeQueueInlineTextChildMutation(change, targetNode);
-      } else if (type === "childList" || type === "nativeAnonymousChildList") {
-        // Get the list of removed and added actors that the client has seen
-        // so that it can keep its ownership tree up to date.
-        let removedActors = [];
-        let addedActors = [];
-        for (let removed of change.removedNodes) {
-          let removedActor = this.getNode(removed);
-          if (!removedActor) {
-            // If the client never encountered this actor we don't need to
-            // mention that it was removed.
-            continue;
-          }
-          // While removed from the tree, nodes are saved as orphaned.
-          this._orphaned.add(removedActor);
-          removedActors.push(removedActor.actorID);
-        }
-        for (let added of change.addedNodes) {
-          let addedActor = this.getNode(added);
-          if (!addedActor) {
-            // If the client never encounted this actor we don't need to tell
-            // it about its addition for ownership tree purposes - if the
-            // client wants to see the new nodes it can ask for children.
-            continue;
-          }
-          // The actor is reconnected to the ownership tree, unorphan
-          // it and let the client know so that its ownership tree is up
-          // to date.
-          this._orphaned.delete(addedActor);
-          addedActors.push(addedActor.actorID);
-        }
-
-        mutation.numChildren = targetActor.numChildren;
-        mutation.removed = removedActors;
-        mutation.added = addedActors;
-
-        let inlineTextChild = this.inlineTextChild(targetActor);
-        if (inlineTextChild) {
-          mutation.inlineTextChild = inlineTextChild.form();
-        }
-      }
-      this.queueMutation(mutation);
-    }
-  },
-
-  /**
-   * Check if the provided mutation could change the way the target element is
-   * inlined with its parent node. If it might, a custom mutation of type
-   * "inlineTextChild" will be queued.
-   *
-   * @param {MutationRecord} mutation
-   *        A characterData type mutation
-   */
-  _maybeQueueInlineTextChildMutation: function (mutation) {
-    let {oldValue, target} = mutation;
-    let newValue = target.nodeValue;
-    let limit = gValueSummaryLength;
-
-    if ((oldValue.length <= limit && newValue.length <= limit) ||
-        (oldValue.length > limit && newValue.length > limit)) {
-      // Bail out if the new & old values are both below/above the size limit.
-      return;
-    }
-
-    let parentActor = this.getNode(target.parentNode);
-    if (!parentActor || parentActor.rawNode.children.length > 0) {
-      // If the parent node has other children, a character data mutation will
-      // not change anything regarding inlining text nodes.
-      return;
-    }
-
-    let inlineTextChild = this.inlineTextChild(parentActor);
-    this.queueMutation({
-      type: "inlineTextChild",
-      target: parentActor.actorID,
-      inlineTextChild:
-        inlineTextChild ? inlineTextChild.form() : undefined
-    });
-  },
-
-  onFrameLoad: function ({ window, isTopLevel }) {
-    let { readyState } = window.document;
-    if (readyState != "interactive" && readyState != "complete") {
-      window.addEventListener("DOMContentLoaded",
-        this.onFrameLoad.bind(this, { window, isTopLevel }),
-        { once: true });
-      return;
-    }
-    if (isTopLevel) {
-      // If we initialize the inspector while the document is loading,
-      // we may already have a root document set in the constructor.
-      if (this.rootDoc && !Cu.isDeadWrapper(this.rootDoc) &&
-          this.rootDoc.defaultView) {
-        this.onFrameUnload({ window: this.rootDoc.defaultView });
-      }
-      // Update all DOM objects references to target the new document.
-      this.rootWin = window;
-      this.rootDoc = window.document;
-      this.rootNode = this.document();
-      this.queueMutation({
-        type: "newRoot",
-        target: this.rootNode.form()
-      });
-      return;
-    }
-    let frame = getFrameElement(window);
-    let frameActor = this.getNode(frame);
-    if (!frameActor) {
-      return;
-    }
-
-    this.queueMutation({
-      type: "frameLoad",
-      target: frameActor.actorID,
-    });
-
-    // Send a childList mutation on the frame.
-    this.queueMutation({
-      type: "childList",
-      target: frameActor.actorID,
-      added: [],
-      removed: []
-    });
-  },
-
-  // Returns true if domNode is in window or a subframe.
-  _childOfWindow: function (window, domNode) {
-    let win = nodeDocument(domNode).defaultView;
-    while (win) {
-      if (win === window) {
-        return true;
-      }
-      win = getFrameElement(win);
-    }
-    return false;
-  },
-
-  onFrameUnload: function ({ window }) {
-    // Any retained orphans that belong to this document
-    // or its children need to be released, and a mutation sent
-    // to notify of that.
-    let releasedOrphans = [];
-
-    for (let retained of this._retainedOrphans) {
-      if (Cu.isDeadWrapper(retained.rawNode) ||
-          this._childOfWindow(window, retained.rawNode)) {
-        this._retainedOrphans.delete(retained);
-        releasedOrphans.push(retained.actorID);
-        this.releaseNode(retained, { force: true });
-      }
-    }
-
-    if (releasedOrphans.length > 0) {
-      this.queueMutation({
-        target: this.rootNode.actorID,
-        type: "unretained",
-        nodes: releasedOrphans
-      });
-    }
-
-    let doc = window.document;
-    let documentActor = this.getNode(doc);
-    if (!documentActor) {
-      return;
-    }
-
-    if (this.rootDoc === doc) {
-      this.rootDoc = null;
-      this.rootNode = null;
-    }
-
-    this.queueMutation({
-      type: "documentUnload",
-      target: documentActor.actorID
-    });
-
-    let walker = this.getDocumentWalker(doc);
-    let parentNode = walker.parentNode();
-    if (parentNode) {
-      // Send a childList mutation on the frame so that clients know
-      // they should reread the children list.
-      this.queueMutation({
-        type: "childList",
-        target: this.getNode(parentNode).actorID,
-        added: [],
-        removed: []
-      });
-    }
-
-    // Need to force a release of this node, because those nodes can't
-    // be accessed anymore.
-    this.releaseNode(documentActor, { force: true });
-  },
-
-  /**
-   * Check if a node is attached to the DOM tree of the current page.
-   * @param {nsIDomNode} rawNode
-   * @return {Boolean} false if the node is removed from the tree or within a
-   * document fragment
-   */
-  _isInDOMTree: function (rawNode) {
-    let walker = this.getDocumentWalker(rawNode);
-    let current = walker.currentNode;
-
-    // Reaching the top of tree
-    while (walker.parentNode()) {
-      current = walker.currentNode;
-    }
-
-    // The top of the tree is a fragment or is not rootDoc, hence rawNode isn't
-    // attached
-    if (current.nodeType === Ci.nsIDOMNode.DOCUMENT_FRAGMENT_NODE ||
-        current !== this.rootDoc) {
-      return false;
-    }
-
-    // Otherwise the top of the tree is rootDoc, hence rawNode is in rootDoc
-    return true;
-  },
-
-  /**
-   * @see _isInDomTree
-   */
-  isInDOMTree: function (node) {
-    if (isNodeDead(node)) {
-      return false;
-    }
-    return this._isInDOMTree(node.rawNode);
-  },
-
-  /**
-   * Given an ObjectActor (identified by its ID), commonly used in the debugger,
-   * webconsole and variablesView, return the corresponding inspector's
-   * NodeActor
-   */
-  getNodeActorFromObjectActor: function (objectActorID) {
-    let actor = this.conn.getActor(objectActorID);
-    if (!actor) {
-      return null;
-    }
-
-    let debuggerObject = this.conn.getActor(objectActorID).obj;
-    let rawNode = debuggerObject.unsafeDereference();
-
-    if (!this._isInDOMTree(rawNode)) {
-      return null;
-    }
-
-    // This is a special case for the document object whereby it is considered
-    // as document.documentElement (the <html> node)
-    if (rawNode.defaultView && rawNode === rawNode.defaultView.document) {
-      rawNode = rawNode.documentElement;
-    }
-
-    return this.attachElement(rawNode);
-  },
-
-  /**
-   * Given a windowID return the NodeActor for the corresponding frameElement,
-   * unless it's the root window
-   */
-  getNodeActorFromWindowID: function (windowID) {
-    let win;
-
-    try {
-      win = Services.wm.getOuterWindowWithId(windowID);
-    } catch (e) {
-      // ignore
-    }
-
-    if (!win) {
-      return { error: "noWindow",
-               message: "The related docshell is destroyed or not found" };
-    } else if (!win.frameElement) {
-      // the frame element of the root document is privileged & thus
-      // inaccessible, so return the document body/element instead
-      return this.attachElement(win.document.body || win.document.documentElement);
-    }
-
-    return this.attachElement(win.frameElement);
-  },
-
-  /**
-   * Given a StyleSheetActor (identified by its ID), commonly used in the
-   * style-editor, get its ownerNode and return the corresponding walker's
-   * NodeActor.
-   * Note that getNodeFromActor was added later and can now be used instead.
-   */
-  getStyleSheetOwnerNode: function (styleSheetActorID) {
-    return this.getNodeFromActor(styleSheetActorID, ["ownerNode"]);
-  },
-
-  /**
-   * This method can be used to retrieve NodeActor for DOM nodes from other
-   * actors in a way that they can later be highlighted in the page, or
-   * selected in the inspector.
-   * If an actor has a reference to a DOM node, and the UI needs to know about
-   * this DOM node (and possibly select it in the inspector), the UI should
-   * first retrieve a reference to the walkerFront:
-   *
-   * // Make sure the inspector/walker have been initialized first.
-   * toolbox.initInspector().then(() => {
-   *  // Retrieve the walker.
-   *  let walker = toolbox.walker;
-   * });
-   *
-   * And then call this method:
-   *
-   * // Get the nodeFront from my actor, passing the ID and properties path.
-   * walker.getNodeFromActor(myActorID, ["element"]).then(nodeFront => {
-   *   // Use the nodeFront, e.g. select the node in the inspector.
-   *   toolbox.getPanel("inspector").selection.setNodeFront(nodeFront);
-   * });
-   *
-   * @param {String} actorID The ID for the actor that has a reference to the
-   * DOM node.
-   * @param {Array} path Where, on the actor, is the DOM node stored. If in the
-   * scope of the actor, the node is available as `this.data.node`, then this
-   * should be ["data", "node"].
-   * @return {NodeActor} The attached NodeActor, or null if it couldn't be
-   * found.
-   */
-  getNodeFromActor: function (actorID, path) {
-    let actor = this.conn.getActor(actorID);
-    if (!actor) {
-      return null;
-    }
-
-    let obj = actor;
-    for (let name of path) {
-      if (!(name in obj)) {
-        return null;
-      }
-      obj = obj[name];
-    }
-
-    return this.attachElement(obj);
-  },
-
-  /**
-   * Returns an instance of the LayoutActor that is used to retrieve CSS layout-related
-   * information.
-   *
-   * @return {LayoutActor}
-   */
-  getLayoutInspector: function () {
-    if (!this.layoutActor) {
-      this.layoutActor = new LayoutActor(this.conn, this.tabActor, this);
-    }
-
-    return this.layoutActor;
-  },
-
-  /**
-   * Returns the offset parent DOMNode of the given node if it exists, otherwise, it
-   * returns null.
-   */
-  getOffsetParent: function (node) {
-    if (isNodeDead(node)) {
-      return null;
-    }
-
-    let offsetParent = node.rawNode.offsetParent;
-
-    if (!offsetParent) {
-      return null;
-    }
-
-    return this._ref(offsetParent);
-  },
-});
-
-/**
- * Server side of the inspector actor, which is used to create
- * inspector-related actors, including the walker.
- */
-exports.InspectorActor = protocol.ActorClassWithSpec(inspectorSpec, {
-  initialize: function (conn, tabActor) {
-    protocol.Actor.prototype.initialize.call(this, conn);
-    this.tabActor = tabActor;
-
-    this._onColorPicked = this._onColorPicked.bind(this);
-    this._onColorPickCanceled = this._onColorPickCanceled.bind(this);
-    this.destroyEyeDropper = this.destroyEyeDropper.bind(this);
-  },
-
-  destroy: function () {
-    protocol.Actor.prototype.destroy.call(this);
-
-    this.destroyEyeDropper();
-
-    this._highlighterPromise = null;
-    this._pageStylePromise = null;
-    this._walkerPromise = null;
-    this.walker = null;
-    this.tabActor = null;
-  },
-
-  get window() {
-    return this.tabActor.window;
-  },
-
-  getWalker: function (options = {}) {
-    if (this._walkerPromise) {
-      return this._walkerPromise;
-    }
-
-    let deferred = defer();
-    this._walkerPromise = deferred.promise;
-
-    let window = this.window;
-    let domReady = () => {
-      let tabActor = this.tabActor;
-      window.removeEventListener("DOMContentLoaded", domReady, true);
-      this.walker = WalkerActor(this.conn, tabActor, options);
-      this.manage(this.walker);
-      this.walker.once("destroyed", () => {
-        this._walkerPromise = null;
-        this._pageStylePromise = null;
-      });
-      deferred.resolve(this.walker);
-    };
-
-    if (window.document.readyState === "loading") {
-      window.addEventListener("DOMContentLoaded", domReady, true);
-    } else {
-      domReady();
-    }
-
-    return this._walkerPromise;
-  },
-
-  getPageStyle: function () {
-    if (this._pageStylePromise) {
-      return this._pageStylePromise;
-    }
-
-    this._pageStylePromise = this.getWalker().then(walker => {
-      let pageStyle = PageStyleActor(this);
-      this.manage(pageStyle);
-      return pageStyle;
-    });
-    return this._pageStylePromise;
-  },
-
-  /**
-   * The most used highlighter actor is the HighlighterActor which can be
-   * conveniently retrieved by this method.
-   * The same instance will always be returned by this method when called
-   * several times.
-   * The highlighter actor returned here is used to highlighter elements's
-   * box-models from the markup-view, box model, console, debugger, ... as
-   * well as select elements with the pointer (pick).
-   *
-   * @param {Boolean} autohide Optionally autohide the highlighter after an
-   * element has been picked
-   * @return {HighlighterActor}
-   */
-  getHighlighter: function (autohide) {
-    if (this._highlighterPromise) {
-      return this._highlighterPromise;
-    }
-
-    this._highlighterPromise = this.getWalker().then(walker => {
-      let highlighter = HighlighterActor(this, autohide);
-      this.manage(highlighter);
-      return highlighter;
-    });
-    return this._highlighterPromise;
-  },
-
-  /**
-   * If consumers need to display several highlighters at the same time or
-   * different types of highlighters, then this method should be used, passing
-   * the type name of the highlighter needed as argument.
-   * A new instance will be created everytime the method is called, so it's up
-   * to the consumer to release it when it is not needed anymore
-   *
-   * @param {String} type The type of highlighter to create
-   * @return {Highlighter} The highlighter actor instance or null if the
-   * typeName passed doesn't match any available highlighter
-   */
-  getHighlighterByType: function (typeName) {
-    if (isTypeRegistered(typeName)) {
-      return CustomHighlighterActor(this, typeName);
-    }
-    return null;
-  },
-
-  /**
-   * Get the node's image data if any (for canvas and img nodes).
-   * Returns an imageData object with the actual data being a LongStringActor
-   * and a size json object.
-   * The image data is transmitted as a base64 encoded png data-uri.
-   * The method rejects if the node isn't an image or if the image is missing
-   *
-   * Accepts a maxDim request parameter to resize images that are larger. This
-   * is important as the resizing occurs server-side so that image-data being
-   * transfered in the longstring back to the client will be that much smaller
-   */
-  getImageDataFromURL: function (url, maxDim) {
-    let img = new this.window.Image();
-    img.src = url;
-
-    // imageToImageData waits for the image to load.
-    return imageToImageData(img, maxDim).then(imageData => {
-      return {
-        data: LongStringActor(this.conn, imageData.data),
-        size: imageData.size
-      };
-    });
-  },
-
-  /**
-   * Resolve a URL to its absolute form, in the scope of a given content window.
-   * @param {String} url.
-   * @param {NodeActor} node If provided, the owner window of this node will be
-   * used to resolve the URL. Otherwise, the top-level content window will be
-   * used instead.
-   * @return {String} url.
-   */
-  resolveRelativeURL: function (url, node) {
-    let document = isNodeDead(node)
-                   ? this.window.document
-                   : nodeDocument(node.rawNode);
-
-    if (!document) {
-      return url;
-    }
-
-    let baseURI = Services.io.newURI(document.location.href);
-    return Services.io.newURI(url, null, baseURI).spec;
-  },
-
-  /**
-   * Create an instance of the eye-dropper highlighter and store it on this._eyeDropper.
-   * Note that for now, a new instance is created every time to deal with page navigation.
-   */
-  createEyeDropper: function () {
-    this.destroyEyeDropper();
-    this._highlighterEnv = new HighlighterEnvironment();
-    this._highlighterEnv.initFromTabActor(this.tabActor);
-    this._eyeDropper = new EyeDropper(this._highlighterEnv);
-  },
-
-  /**
-   * Destroy the current eye-dropper highlighter instance.
-   */
-  destroyEyeDropper: function () {
-    if (this._eyeDropper) {
-      this.cancelPickColorFromPage();
-      this._eyeDropper.destroy();
-      this._eyeDropper = null;
-      this._highlighterEnv.destroy();
-      this._highlighterEnv = null;
-    }
-  },
-
-  /**
-   * Pick a color from the page using the eye-dropper. This method doesn't return anything
-   * but will cause events to be sent to the front when a color is picked or when the user
-   * cancels the picker.
-   * @param {Object} options
-   */
-  pickColorFromPage: function (options) {
-    this.createEyeDropper();
-    this._eyeDropper.show(this.window.document.documentElement, options);
-    this._eyeDropper.once("selected", this._onColorPicked);
-    this._eyeDropper.once("canceled", this._onColorPickCanceled);
-    this.tabActor.once("will-navigate", this.destroyEyeDropper);
-  },
-
-  /**
-   * After the pickColorFromPage method is called, the only way to dismiss the eye-dropper
-   * highlighter is for the user to click in the page and select a color. If you need to
-   * dismiss the eye-dropper programatically instead, use this method.
-   */
-  cancelPickColorFromPage: function () {
-    if (this._eyeDropper) {
-      this._eyeDropper.hide();
-      this._eyeDropper.off("selected", this._onColorPicked);
-      this._eyeDropper.off("canceled", this._onColorPickCanceled);
-      this.tabActor.off("will-navigate", this.destroyEyeDropper);
-    }
-  },
-
-  /**
-   * Check if the current document supports highlighters using a canvasFrame anonymous
-   * content container (ie all highlighters except the SimpleOutlineHighlighter).
-   * It is impossible to detect the feature programmatically as some document types simply
-   * don't render the canvasFrame without throwing any error.
-   */
-  supportsHighlighters: function () {
-    let doc = this.tabActor.window.document;
-    let ns = doc.documentElement.namespaceURI;
-
-    // XUL documents do not support insertAnonymousContent().
-    if (ns === XUL_NS) {
-      return false;
-    }
-
-    // SVG documents do not render the canvasFrame (see Bug 1157592).
-    if (ns === SVG_NS) {
-      return false;
-    }
-
-    return true;
-  },
-
-  _onColorPicked: function (e, color) {
-    this.emit("color-picked", color);
-  },
-
-  _onColorPickCanceled: function () {
-    this.emit("color-pick-canceled");
-  }
-});
-
-// Exported for test purposes.
-exports._documentWalker = DocumentWalker;
-
-function nodeDocument(node) {
-  if (Cu.isDeadWrapper(node)) {
-    return null;
-  }
-  return node.ownerDocument ||
-         (node.nodeType == Ci.nsIDOMNode.DOCUMENT_NODE ? node : null);
-}
-
-function nodeDocshell(node) {
-  let doc = node ? nodeDocument(node) : null;
-  let win = doc ? doc.defaultView : null;
-  if (win) {
-    return win.QueryInterface(Ci.nsIInterfaceRequestor)
-              .getInterface(Ci.nsIDocShell);
-  }
-  return null;
-}
-
-function isNodeDead(node) {
-  return !node || !node.rawNode || Cu.isDeadWrapper(node.rawNode);
-}
-
-/**
- * Wrapper for inDeepTreeWalker.  Adds filtering to the traversal methods.
- * See inDeepTreeWalker for more information about the methods.
- *
- * @param {DOMNode} node
- * @param {Window} rootWin
- * @param {Number} whatToShow
- *        See nodeFilterConstants / inIDeepTreeWalker for options.
- * @param {Function} filter
- *        A custom filter function Taking in a DOMNode and returning an Int. See
- *        WalkerActor.nodeFilter for an example.
- * @param {String} skipTo
- *        Either SKIP_TO_PARENT or SKIP_TO_SIBLING. If the provided node is not compatible
- *        with the filter function for this walker, try to find a compatible one either
- *        in the parents or in the siblings of the node.
- */
-function DocumentWalker(node, rootWin,
-    whatToShow = nodeFilterConstants.SHOW_ALL,
-    filter = standardTreeWalkerFilter,
-    skipTo = SKIP_TO_PARENT) {
-  if (Cu.isDeadWrapper(rootWin) || !rootWin.location) {
-    throw new Error("Got an invalid root window in DocumentWalker");
-  }
-
-  this.walker = Cc["@mozilla.org/inspector/deep-tree-walker;1"]
-    .createInstance(Ci.inIDeepTreeWalker);
-  this.walker.showAnonymousContent = true;
-  this.walker.showSubDocuments = true;
-  this.walker.showDocumentsAsNodes = true;
-  this.walker.init(rootWin.document, whatToShow);
-  this.filter = filter;
-
-  // Make sure that the walker knows about the initial node (which could
-  // be skipped due to a filter).
-  this.walker.currentNode = this.getStartingNode(node, skipTo);
-}
-
-DocumentWalker.prototype = {
-  get whatToShow() {
-    return this.walker.whatToShow;
-  },
-  get currentNode() {
-    return this.walker.currentNode;
-  },
-  set currentNode(val) {
-    this.walker.currentNode = val;
-  },
-
-  parentNode: function () {
-    return this.walker.parentNode();
-  },
-
-  nextNode: function () {
-    let node = this.walker.currentNode;
-    if (!node) {
-      return null;
-    }
-
-    let nextNode = this.walker.nextNode();
-    while (nextNode && this.isSkippedNode(nextNode)) {
-      nextNode = this.walker.nextNode();
-    }
-
-    return nextNode;
-  },
-
-  firstChild: function () {
-    let node = this.walker.currentNode;
-    if (!node) {
-      return null;
-    }
-
-    let firstChild = this.walker.firstChild();
-    while (firstChild && this.isSkippedNode(firstChild)) {
-      firstChild = this.walker.nextSibling();
-    }
-
-    return firstChild;
-  },
-
-  lastChild: function () {
-    let node = this.walker.currentNode;
-    if (!node) {
-      return null;
-    }
-
-    let lastChild = this.walker.lastChild();
-    while (lastChild && this.isSkippedNode(lastChild)) {
-      lastChild = this.walker.previousSibling();
-    }
-
-    return lastChild;
-  },
-
-  previousSibling: function () {
-    let node = this.walker.previousSibling();
-    while (node && this.isSkippedNode(node)) {
-      node = this.walker.previousSibling();
-    }
-    return node;
-  },
-
-  nextSibling: function () {
-    let node = this.walker.nextSibling();
-    while (node && this.isSkippedNode(node)) {
-      node = this.walker.nextSibling();
-    }
-    return node;
-  },
-
-  getStartingNode: function (node, skipTo) {
-    // Keep a reference on the starting node in case we can't find a node compatible with
-    // the filter.
-    let startingNode = node;
-
-    if (skipTo === SKIP_TO_PARENT) {
-      while (node && this.isSkippedNode(node)) {
-        node = node.parentNode;
-      }
-    } else if (skipTo === SKIP_TO_SIBLING) {
-      node = this.getClosestAcceptedSibling(node);
-    }
-
-    return node || startingNode;
-  },
-
-  /**
-   * Loop on all of the provided node siblings until finding one that is compliant with
-   * the filter function.
-   */
-  getClosestAcceptedSibling: function (node) {
-    if (this.filter(node) === nodeFilterConstants.FILTER_ACCEPT) {
-      // node is already valid, return immediately.
-      return node;
-    }
-
-    // Loop on starting node siblings.
-    let previous = node;
-    let next = node;
-    while (previous || next) {
-      previous = previous && previous.previousSibling;
-      next = next && next.nextSibling;
-
-      if (previous && this.filter(previous) === nodeFilterConstants.FILTER_ACCEPT) {
-        // A valid node was found in the previous siblings of the node.
-        return previous;
-      }
-
-      if (next && this.filter(next) === nodeFilterConstants.FILTER_ACCEPT) {
-        // A valid node was found in the next siblings of the node.
-        return next;
-      }
-    }
-
-    return null;
-  },
-
-  isSkippedNode: function (node) {
-    return this.filter(node) === nodeFilterConstants.FILTER_SKIP;
-  },
-};
-
-function isInXULDocument(el) {
-  let doc = nodeDocument(el);
-  return doc &&
-         doc.documentElement &&
-         doc.documentElement.namespaceURI === XUL_NS;
-}
-
-/**
- * This DeepTreeWalker filter skips whitespace text nodes and anonymous
- * content with the exception of ::before and ::after and anonymous content
- * in XUL document (needed to show all elements in the browser toolbox).
- */
-function standardTreeWalkerFilter(node) {
-  // ::before and ::after are native anonymous content, but we always
-  // want to show them
-  if (node.nodeName === "_moz_generated_content_before" ||
-      node.nodeName === "_moz_generated_content_after") {
-    return nodeFilterConstants.FILTER_ACCEPT;
-  }
-
-  // Ignore empty whitespace text nodes that do not impact the layout.
-  if (isWhitespaceTextNode(node)) {
-    return nodeHasSize(node)
-           ? nodeFilterConstants.FILTER_ACCEPT
-           : nodeFilterConstants.FILTER_SKIP;
-  }
-
-  // Ignore all native and XBL anonymous content inside a non-XUL document.
-  // We need to do this to skip things like form controls, scrollbars,
-  // video controls, etc (see bug 1187482).
-  if (!isInXULDocument(node) && (isXBLAnonymous(node) ||
-                                  isNativeAnonymous(node))) {
-    return nodeFilterConstants.FILTER_SKIP;
-  }
-
-  return nodeFilterConstants.FILTER_ACCEPT;
-}
-
-/**
- * This DeepTreeWalker filter is like standardTreeWalkerFilter except that
- * it also includes all anonymous content (like internal form controls).
- */
-function allAnonymousContentTreeWalkerFilter(node) {
-  // Ignore empty whitespace text nodes that do not impact the layout.
-  if (isWhitespaceTextNode(node)) {
-    return nodeHasSize(node)
-           ? nodeFilterConstants.FILTER_ACCEPT
-           : nodeFilterConstants.FILTER_SKIP;
-  }
-  return nodeFilterConstants.FILTER_ACCEPT;
-}
-
-/**
- * Is the given node a text node composed of whitespace only?
- * @param {DOMNode} node
- * @return {Boolean}
- */
-function isWhitespaceTextNode(node) {
-  return node.nodeType == Ci.nsIDOMNode.TEXT_NODE && !/[^\s]/.exec(node.nodeValue);
-}
-
-/**
- * Does the given node have non-0 width and height?
- * @param {DOMNode} node
- * @return {Boolean}
- */
-function nodeHasSize(node) {
-  if (!node.getBoxQuads) {
-    return false;
-  }
-
-  let quads = node.getBoxQuads();
-  return quads.length && quads.some(quad => quad.bounds.width && quad.bounds.height);
-}
-
-/**
- * Returns a promise that is settled once the given HTMLImageElement has
- * finished loading.
- *
- * @param {HTMLImageElement} image - The image element.
- * @param {Number} timeout - Maximum amount of time the image is allowed to load
- * before the waiting is aborted. Ignored if flags.testing is set.
- *
- * @return {Promise} that is fulfilled once the image has loaded. If the image
- * fails to load or the load takes too long, the promise is rejected.
- */
-function ensureImageLoaded(image, timeout) {
-  let { HTMLImageElement } = image.ownerGlobal;
-  if (!(image instanceof HTMLImageElement)) {
-    return promise.reject("image must be an HTMLImageELement");
-  }
-
-  if (image.complete) {
-    // The image has already finished loading.
-    return promise.resolve();
-  }
-
-  // This image is still loading.
-  let onLoad = AsyncUtils.listenOnce(image, "load");
-
-  // Reject if loading fails.
-  let onError = AsyncUtils.listenOnce(image, "error").then(() => {
-    return promise.reject("Image '" + image.src + "' failed to load.");
-  });
-
-  // Don't timeout when testing. This is never settled.
-  let onAbort = new Promise(() => {});
-
-  if (!flags.testing) {
-    // Tests are not running. Reject the promise after given timeout.
-    onAbort = DevToolsUtils.waitForTime(timeout).then(() => {
-      return promise.reject("Image '" + image.src + "' took too long to load.");
-    });
-  }
-
-  // See which happens first.
-  return promise.race([onLoad, onError, onAbort]);
-}
-
-/**
- * Given an <img> or <canvas> element, return the image data-uri. If @param node
- * is an <img> element, the method waits a while for the image to load before
- * the data is generated. If the image does not finish loading in a reasonable
- * time (IMAGE_FETCHING_TIMEOUT milliseconds) the process aborts.
- *
- * @param {HTMLImageElement|HTMLCanvasElement} node - The <img> or <canvas>
- * element, or Image() object. Other types cause the method to reject.
- * @param {Number} maxDim - Optionally pass a maximum size you want the longest
- * side of the image to be resized to before getting the image data.
-
- * @return {Promise} A promise that is fulfilled with an object containing the
- * data-uri and size-related information:
- * { data: "...",
- *   size: {
- *     naturalWidth: 400,
- *     naturalHeight: 300,
- *     resized: true }
- *  }.
- *
- * If something goes wrong, the promise is rejected.
- */
-var imageToImageData = Task.async(function* (node, maxDim) {
-  let { HTMLCanvasElement, HTMLImageElement } = node.ownerGlobal;
-
-  let isImg = node instanceof HTMLImageElement;
-  let isCanvas = node instanceof HTMLCanvasElement;
-
-  if (!isImg && !isCanvas) {
-    throw new Error("node is not a <canvas> or <img> element.");
-  }
-
-  if (isImg) {
-    // Ensure that the image is ready.
-    yield ensureImageLoaded(node, IMAGE_FETCHING_TIMEOUT);
-  }
-
-  // Get the image resize ratio if a maxDim was provided
-  let resizeRatio = 1;
-  let imgWidth = node.naturalWidth || node.width;
-  let imgHeight = node.naturalHeight || node.height;
-  let imgMax = Math.max(imgWidth, imgHeight);
-  if (maxDim && imgMax > maxDim) {
-    resizeRatio = maxDim / imgMax;
-  }
-
-  // Extract the image data
-  let imageData;
-  // The image may already be a data-uri, in which case, save ourselves the
-  // trouble of converting via the canvas.drawImage.toDataURL method, but only
-  // if the image doesn't need resizing
-  if (isImg && node.src.startsWith("data:") && resizeRatio === 1) {
-    imageData = node.src;
-  } else {
-    // Create a canvas to copy the rawNode into and get the imageData from
-    let canvas = node.ownerDocument.createElementNS(XHTML_NS, "canvas");
-    canvas.width = imgWidth * resizeRatio;
-    canvas.height = imgHeight * resizeRatio;
-    let ctx = canvas.getContext("2d");
-
-    // Copy the rawNode image or canvas in the new canvas and extract data
-    ctx.drawImage(node, 0, 0, canvas.width, canvas.height);
-    imageData = canvas.toDataURL("image/png");
-  }
-
-  return {
-    data: imageData,
-    size: {
-      naturalWidth: imgWidth,
-      naturalHeight: imgHeight,
-      resized: resizeRatio !== 1
-    }
-  };
-});
+exports.NodeActor = NodeActor;
+exports.NodeListActor = NodeListActor;
copy from devtools/server/actors/inspector/inspector.js
copy to devtools/server/actors/inspector/utils.js
--- a/devtools/server/actors/inspector/inspector.js
+++ b/devtools/server/actors/inspector/utils.js
@@ -1,190 +1,31 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
-/**
- * Here's the server side of the remote inspector.
- *
- * The WalkerActor is the client's view of the debuggee's DOM.  It's gives
- * the client a tree of NodeActor objects.
- *
- * The walker presents the DOM tree mostly unmodified from the source DOM
- * tree, but with a few key differences:
- *
- *  - Empty text nodes are ignored.  This is pretty typical of developer
- *    tools, but maybe we should reconsider that on the server side.
- *  - iframes with documents loaded have the loaded document as the child,
- *    the walker provides one big tree for the whole document tree.
- *
- * There are a few ways to get references to NodeActors:
- *
- *   - When you first get a WalkerActor reference, it comes with a free
- *     reference to the root document's node.
- *   - Given a node, you can ask for children, siblings, and parents.
- *   - You can issue querySelector and querySelectorAll requests to find
- *     other elements.
- *   - Requests that return arbitrary nodes from the tree (like querySelector
- *     and querySelectorAll) will also return any nodes the client hasn't
- *     seen in order to have a complete set of parents.
- *
- * Once you have a NodeFront, you should be able to answer a few questions
- * without further round trips, like the node's name, namespace/tagName,
- * attributes, etc.  Other questions (like a text node's full nodeValue)
- * might require another round trip.
- *
- * The protocol guarantees that the client will always know the parent of
- * any node that is returned by the server.  This means that some requests
- * (like querySelector) will include the extra nodes needed to satisfy this
- * requirement.  The client keeps track of this parent relationship, so the
- * node fronts form a tree that is a subset of the actual DOM tree.
- *
- *
- * We maintain this guarantee to support the ability to release subtrees on
- * the client - when a node is disconnected from the DOM tree we want to be
- * able to free the client objects for all the children nodes.
- *
- * So to be able to answer "all the children of a given node that we have
- * seen on the client side", we guarantee that every time we've seen a node,
- * we connect it up through its parents.
- */
+const {Ci, Cu} = require("chrome");
+
+const promise = require("promise");
+const {Task} = require("devtools/shared/task");
 
-const {Cc, Ci, Cu} = require("chrome");
-const Services = require("Services");
-const protocol = require("devtools/shared/protocol");
-const {LongStringActor} = require("devtools/server/actors/string");
-const promise = require("promise");
-const defer = require("devtools/shared/defer");
-const {Task} = require("devtools/shared/task");
-const EventEmitter = require("devtools/shared/event-emitter");
-const InspectorUtils = require("InspectorUtils");
-
-const {walkerSpec, inspectorSpec} = require("devtools/shared/specs/inspector");
-const {nodeSpec, nodeListSpec} = require("devtools/shared/specs/node");
-
+loader.lazyRequireGetter(this, "AsyncUtils", "devtools/shared/async-utils");
+loader.lazyRequireGetter(this, "flags", "devtools/shared/flags");
 loader.lazyRequireGetter(this, "DevToolsUtils", "devtools/shared/DevToolsUtils");
-loader.lazyRequireGetter(this, "AsyncUtils", "devtools/shared/async-utils");
-loader.lazyRequireGetter(this, "CssLogic", "devtools/server/css-logic", true);
-loader.lazyRequireGetter(this, "findCssSelector", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "getCssPath", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "getXPath", "devtools/shared/inspector/css-logic", true);
-loader.lazyRequireGetter(this, "colorUtils", "devtools/shared/css/color", true);
-loader.lazyRequireGetter(this, "EyeDropper", "devtools/server/actors/highlighters/eye-dropper", true);
-loader.lazyRequireGetter(this, "WalkerSearch", "devtools/server/actors/utils/walker-search", true);
-loader.lazyRequireGetter(this, "PageStyleActor", "devtools/server/actors/styles", true);
-loader.lazyRequireGetter(this, "getFontPreviewData", "devtools/server/actors/styles", true);
-loader.lazyRequireGetter(this, "flags", "devtools/shared/flags");
-loader.lazyRequireGetter(this, "throttle", "devtools/shared/throttle", true);
-loader.lazyRequireGetter(this, "LayoutActor", "devtools/server/actors/layout", true);
-loader.lazyRequireGetter(this, "HighlighterActor", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "CustomHighlighterActor", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "isTypeRegistered", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "HighlighterEnvironment", "devtools/server/actors/highlighters", true);
-loader.lazyRequireGetter(this, "EventParsers", "devtools/server/event-parsers", true);
-loader.lazyRequireGetter(this, "isAnonymous", "devtools/shared/layout/utils", true);
+loader.lazyRequireGetter(this, "nodeFilterConstants", "devtools/shared/dom-node-filter-constants");
+
 loader.lazyRequireGetter(this, "isNativeAnonymous", "devtools/shared/layout/utils", true);
 loader.lazyRequireGetter(this, "isXBLAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "isShadowAnonymous", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "getFrameElement", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "loadSheet", "devtools/shared/layout/utils", true);
-loader.lazyRequireGetter(this, "getLayoutChangesObserver", "devtools/server/actors/reflow", true);
-loader.lazyRequireGetter(this, "releaseLayoutChangesObserver", "devtools/server/actors/reflow", true);
-loader.lazyRequireGetter(this, "nodeFilterConstants", "devtools/shared/dom-node-filter-constants");
 
-loader.lazyServiceGetter(this, "DOMParser",
-  "@mozilla.org/xmlextras/domparser;1", "nsIDOMParser");
-
-loader.lazyServiceGetter(this, "eventListenerService",
-  "@mozilla.org/eventlistenerservice;1", "nsIEventListenerService");
-
-const FONT_FAMILY_PREVIEW_TEXT = "The quick brown fox jumps over the lazy dog";
-const FONT_FAMILY_PREVIEW_TEXT_SIZE = 20;
-const PSEUDO_CLASSES = [":hover", ":active", ":focus"];
-const HIDDEN_CLASS = "__fx-devtools-hide-shortcut__";
-const SVG_NS = "http://www.w3.org/2000/svg";
 const XHTML_NS = "http://www.w3.org/1999/xhtml";
 const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
 const IMAGE_FETCHING_TIMEOUT = 500;
 
-// Minimum delay between two "new-mutations" events.
-const MUTATIONS_THROTTLING_DELAY = 100;
-// List of mutation types that should -not- be throttled.
-const IMMEDIATE_MUTATIONS = [
-  "documentUnload",
-  "frameLoad",
-  "newRoot",
-  "pseudoClassLock",
-];
-
-// SKIP_TO_* arguments are used with the DocumentWalker, driving the strategy to use if
-// the starting node is incompatible with the filter function of the walker.
-const SKIP_TO_PARENT = "SKIP_TO_PARENT";
-const SKIP_TO_SIBLING = "SKIP_TO_SIBLING";
-
-// The possible completions to a ':' with added score to give certain values
-// some preference.
-const PSEUDO_SELECTORS = [
-  [":active", 1],
-  [":hover", 1],
-  [":focus", 1],
-  [":visited", 0],
-  [":link", 0],
-  [":first-letter", 0],
-  [":first-child", 2],
-  [":before", 2],
-  [":after", 2],
-  [":lang(", 0],
-  [":not(", 3],
-  [":first-of-type", 0],
-  [":last-of-type", 0],
-  [":only-of-type", 0],
-  [":only-child", 2],
-  [":nth-child(", 3],
-  [":nth-last-child(", 0],
-  [":nth-of-type(", 0],
-  [":nth-last-of-type(", 0],
-  [":last-child", 2],
-  [":root", 0],
-  [":empty", 0],
-  [":target", 0],
-  [":enabled", 0],
-  [":disabled", 0],
-  [":checked", 1],
-  ["::selection", 0]
-];
-
-var HELPER_SHEET = "data:text/css;charset=utf-8," + encodeURIComponent(`
-  .__fx-devtools-hide-shortcut__ {
-    visibility: hidden !important;
-  }
-
-  :-moz-devtools-highlighted {
-    outline: 2px dashed #F06!important;
-    outline-offset: -2px !important;
-  }
-`);
-
-/**
- * We only send nodeValue up to a certain size by default.  This stuff
- * controls that size.
- */
-exports.DEFAULT_VALUE_SUMMARY_LENGTH = 50;
-var gValueSummaryLength = exports.DEFAULT_VALUE_SUMMARY_LENGTH;
-
-exports.getValueSummaryLength = function () {
-  return gValueSummaryLength;
-};
-
-exports.setValueSummaryLength = function (val) {
-  gValueSummaryLength = val;
-};
-
 /**
  * Returns the properly cased version of the node's tag name, which can be
  * used when displaying said name in the UI.
  *
  * @param  {Node} rawNode
  *         Node for which we want the display name
  * @return {String}
  *         Properly cased version of the node tag name
@@ -192,3026 +33,29 @@ exports.setValueSummaryLength = function
 const getNodeDisplayName = function (rawNode) {
   if (rawNode.nodeName && !rawNode.localName) {
     // The localName & prefix APIs have been moved from the Node interface to the Element
     // interface. Use Node.nodeName as a fallback.
     return rawNode.nodeName;
   }
   return (rawNode.prefix ? rawNode.prefix + ":" : "") + rawNode.localName;
 };
-exports.getNodeDisplayName = getNodeDisplayName;
-
-/**
- * Server side of the node actor.
- */
-var NodeActor = exports.NodeActor = protocol.ActorClassWithSpec(nodeSpec, {
-  initialize: function (walker, node) {
-    protocol.Actor.prototype.initialize.call(this, null);
-    this.walker = walker;
-    this.rawNode = node;
-    this._eventParsers = new EventParsers().parsers;
-
-    // Storing the original display of the node, to track changes when reflows
-    // occur
-    this.wasDisplayed = this.isDisplayed;
-  },
-
-  toString: function () {
-    return "[NodeActor " + this.actorID + " for " +
-      this.rawNode.toString() + "]";
-  },
-
-  /**
-   * Instead of storing a connection object, the NodeActor gets its connection
-   * from its associated walker.
-   */
-  get conn() {
-    return this.walker.conn;
-  },
-
-  isDocumentElement: function () {
-    return this.rawNode.ownerDocument &&
-           this.rawNode.ownerDocument.documentElement === this.rawNode;
-  },
-
-  destroy: function () {
-    protocol.Actor.prototype.destroy.call(this);
-
-    if (this.mutationObserver) {
-      if (!Cu.isDeadWrapper(this.mutationObserver)) {
-        this.mutationObserver.disconnect();
-      }
-      this.mutationObserver = null;
-    }
-    this.rawNode = null;
-    this.walker = null;
-  },
-
-  // Returns the JSON representation of this object over the wire.
-  form: function (detail) {
-    if (detail === "actorid") {
-      return this.actorID;
-    }
-
-    let parentNode = this.walker.parentNode(this);
-    let inlineTextChild = this.walker.inlineTextChild(this);
-
-    let form = {
-      actor: this.actorID,
-      baseURI: this.rawNode.baseURI,
-      parent: parentNode ? parentNode.actorID : undefined,
-      nodeType: this.rawNode.nodeType,
-      namespaceURI: this.rawNode.namespaceURI,
-      nodeName: this.rawNode.nodeName,
-      nodeValue: this.rawNode.nodeValue,
-      displayName: getNodeDisplayName(this.rawNode),
-      numChildren: this.numChildren,
-      inlineTextChild: inlineTextChild ? inlineTextChild.form() : undefined,
-
-      // doctype attributes
-      name: this.rawNode.name,
-      publicId: this.rawNode.publicId,
-      systemId: this.rawNode.systemId,
-
-      attrs: this.writeAttrs(),
-      isBeforePseudoElement: this.isBeforePseudoElement,
-      isAfterPseudoElement: this.isAfterPseudoElement,
-      isAnonymous: isAnonymous(this.rawNode),
-      isNativeAnonymous: isNativeAnonymous(this.rawNode),
-      isXBLAnonymous: isXBLAnonymous(this.rawNode),
-      isShadowAnonymous: isShadowAnonymous(this.rawNode),
-      pseudoClassLocks: this.writePseudoClassLocks(),
-
-      isDisplayed: this.isDisplayed,
-      isInHTMLDocument: this.rawNode.ownerDocument &&
-        this.rawNode.ownerDocument.contentType === "text/html",
-      hasEventListeners: this._hasEventListeners,
-    };
-
-    if (this.isDocumentElement()) {
-      form.isDocumentElement = true;
-    }
-
-    // Add an extra API for custom properties added by other
-    // modules/extensions.
-    form.setFormProperty = (name, value) => {
-      if (!form.props) {
-        form.props = {};
-      }
-      form.props[name] = value;
-    };
-
-    // Fire an event so, other modules can create its own properties
-    // that should be passed to the client (within the form.props field).
-    EventEmitter.emit(NodeActor, "form", {
-      target: this,
-      data: form
-    });
-
-    return form;
-  },
-
-  /**
-   * Watch the given document node for mutations using the DOM observer
-   * API.
-   */
-  watchDocument: function (callback) {
-    let node = this.rawNode;
-    // Create the observer on the node's actor.  The node will make sure
-    // the observer is cleaned up when the actor is released.
-    let observer = new node.defaultView.MutationObserver(callback);
-    observer.mergeAttributeRecords = true;
-    observer.observe(node, {
-      nativeAnonymousChildList: true,
-      attributes: true,
-      characterData: true,
-      characterDataOldValue: true,
-      childList: true,
-      subtree: true
-    });
-    this.mutationObserver = observer;
-  },
-
-  get isBeforePseudoElement() {
-    return this.rawNode.nodeName === "_moz_generated_content_before";
-  },
-
-  get isAfterPseudoElement() {
-    return this.rawNode.nodeName === "_moz_generated_content_after";
-  },
-
-  // Estimate the number of children that the walker will return without making
-  // a call to children() if possible.
-  get numChildren() {
-    // For pseudo elements, childNodes.length returns 1, but the walker
-    /