--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -351,16 +351,149 @@ module.exports = {
       "no-redeclare": "off",
       "no-sequences": "off",
       "no-shadow": "off",
       "no-unused-vars": "off",
       "no-useless-call": "off",
     }
   }, {
     "files": [
+      "toolkit/components/aboutmemory/tests/test_aboutmemory.xhtml",
+      "toolkit/components/aboutmemory/tests/test_aboutmemory2.xhtml",
+      "toolkit/components/aboutmemory/tests/test_aboutmemory3.xhtml",
+      "toolkit/components/aboutmemory/tests/test_aboutmemory4.xhtml",
+      "toolkit/components/aboutmemory/tests/test_aboutmemory5.xhtml",
+      "toolkit/components/aboutmemory/tests/test_aboutmemory7.xhtml",
+      "toolkit/components/aboutmemory/tests/test_dumpGCAndCCLogsToFile.xhtml",
+      "toolkit/components/aboutmemory/tests/test_memoryReporters.xhtml",
+      "toolkit/components/aboutmemory/tests/test_memoryReporters2.xhtml",
+      "toolkit/components/aboutmemory/tests/test_sqliteMultiReporter.xhtml",
+      "toolkit/components/ctypes/tests/chrome/test_ctypes.xhtml",
+      "toolkit/components/osfile/tests/mochi/test_osfile_back.xhtml",
+      "toolkit/components/osfile/tests/mochi/test_osfile_comms.xhtml",
+      "toolkit/components/osfile/tests/mochi/test_osfile_front.xhtml",
+      "toolkit/components/places/tests/chrome/browser_disableglobalhistory.xhtml",
+      "toolkit/components/places/tests/chrome/test_browser_disableglobalhistory.xhtml",
+      "toolkit/components/places/tests/chrome/test_favicon_annotations.xhtml",
+      "toolkit/components/workerloader/tests/test_loading.xhtml",
+      "toolkit/content/tests/chrome/bug263683_window.xhtml",
+      "toolkit/content/tests/chrome/bug304188_window.xhtml",
+      "toolkit/content/tests/chrome/bug331215_window.xhtml",
+      "toolkit/content/tests/chrome/bug360437_window.xhtml",
+      "toolkit/content/tests/chrome/bug366992_window.xhtml",
+      "toolkit/content/tests/chrome/bug409624_window.xhtml",
+      "toolkit/content/tests/chrome/bug429723_window.xhtml",
+      "toolkit/content/tests/chrome/bug451540_window.xhtml",
+      "toolkit/content/tests/chrome/dialog_dialogfocus.xhtml",
+      "toolkit/content/tests/chrome/findbar_entireword_window.xhtml",
+      "toolkit/content/tests/chrome/findbar_events_window.xhtml",
+      "toolkit/content/tests/chrome/findbar_window.xhtml",
+      "toolkit/content/tests/chrome/frame_popup_anchor.xhtml",
+      "toolkit/content/tests/chrome/frame_subframe_origin_subframe1.xhtml",
+      "toolkit/content/tests/chrome/frame_subframe_origin_subframe2.xhtml",   
+      "toolkit/content/tests/chrome/test_arrowpanel.xhtml",
+      "toolkit/content/tests/chrome/test_autocomplete2.xhtml",
+      "toolkit/content/tests/chrome/test_autocomplete3.xhtml",
+      "toolkit/content/tests/chrome/test_autocomplete4.xhtml",
+      "toolkit/content/tests/chrome/test_autocomplete5.xhtml",
+      "toolkit/content/tests/chrome/test_autocomplete_emphasis.xhtml",
+      "toolkit/content/tests/chrome/test_autocomplete_mac_caret.xhtml",
+      "toolkit/content/tests/chrome/test_autocomplete_placehold_last_complete.xhtml",
+      "toolkit/content/tests/chrome/test_browser_drop.xhtml",
+      "toolkit/content/tests/chrome/test_bug1048178.xhtml",
+      "toolkit/content/tests/chrome/test_bug382990.xhtml",  
+      "toolkit/content/tests/chrome/test_bug437844.xhtml",
+      "toolkit/content/tests/chrome/test_bug624329.xhtml",
+      "toolkit/content/tests/chrome/test_bug792324.xhtml",
+      "toolkit/content/tests/chrome/test_contextmenu_list.xhtml",
+      "toolkit/content/tests/chrome/test_cursorsnap.xhtml",
+      "toolkit/content/tests/chrome/test_dialogfocus.xhtml",
+      "toolkit/content/tests/chrome/test_hiddenitems.xhtml",
+      "toolkit/content/tests/chrome/test_hiddenpaging.xhtml",
+      "toolkit/content/tests/chrome/test_maximized_persist.xhtml",
+      "toolkit/content/tests/chrome/test_menu.xhtml",
+      "toolkit/content/tests/chrome/test_menuitem_blink.xhtml",
+      "toolkit/content/tests/chrome/test_menulist.xhtml",
+      "toolkit/content/tests/chrome/test_menulist_keynav.xhtml",
+      "toolkit/content/tests/chrome/test_mousescroll.xhtml",
+      "toolkit/content/tests/chrome/test_mozinputbox_dictionary.xhtml",
+      "toolkit/content/tests/chrome/test_notificationbox.xhtml",
+      "toolkit/content/tests/chrome/test_panel_focus.xhtml",
+      "toolkit/content/tests/chrome/test_popup_keys.xhtml",
+      "toolkit/content/tests/chrome/test_popup_scaled.xhtml",
+      "toolkit/content/tests/chrome/test_popupincontent.xhtml",
+      "toolkit/content/tests/chrome/test_popupremoving.xhtml",
+      "toolkit/content/tests/chrome/test_popupremoving_frame.xhtml",    
+      "toolkit/content/tests/chrome/test_position.xhtml",
+      "toolkit/content/tests/chrome/test_preferences.xhtml",
+      "toolkit/content/tests/chrome/test_richlistbox.xhtml",
+      "toolkit/content/tests/chrome/test_righttoleft.xhtml",
+      "toolkit/content/tests/chrome/test_screenPersistence.xhtml",
+      "toolkit/content/tests/chrome/test_scrollbar.xhtml",
+      "toolkit/content/tests/chrome/test_showcaret.xhtml",
+      "toolkit/content/tests/chrome/test_tabbox.xhtml",
+      "toolkit/content/tests/chrome/test_textbox_search.xhtml",
+      "toolkit/content/tests/chrome/test_tree_view.xhtml",
+      "toolkit/content/tests/chrome/window_browser_drop.xhtml",   
+      "toolkit/content/tests/chrome/window_cursorsnap_dialog.xhtml",
+      "toolkit/content/tests/chrome/window_cursorsnap_wizard.xhtml",
+      "toolkit/content/tests/chrome/window_keys.xhtml",
+      "toolkit/content/tests/chrome/window_largemenu.xhtml",
+      "toolkit/content/tests/chrome/window_panel.xhtml",
+      "toolkit/content/tests/chrome/window_panel_anchoradjust.xhtml",
+      "toolkit/content/tests/chrome/window_popup_preventdefault_chrome.xhtml",
+      "toolkit/content/tests/chrome/window_preferences.xhtml",
+      "toolkit/content/tests/chrome/window_preferences3.xhtml",
+      "toolkit/content/tests/chrome/window_preferences_beforeaccept.xhtml",
+      "toolkit/content/tests/chrome/window_preferences_commandretarget.xhtml",  
+      "toolkit/content/tests/chrome/window_preferences_onsyncfrompreference.xhtml",
+      "toolkit/content/tests/chrome/window_subframe_origin.xhtml",
+      "toolkit/content/tests/chrome/window_titlebar.xhtml",
+      "toolkit/content/tests/chrome/window_tooltip.xhtml",
+      "toolkit/content/tests/widgets/test_contextmenu_menugroup.xhtml",
+      "toolkit/content/tests/widgets/test_contextmenu_nested.xhtml",
+      "toolkit/content/tests/widgets/test_editor_currentURI.xhtml",
+      "toolkit/content/tests/widgets/test_popupanchor.xhtml",
+      "toolkit/content/tests/widgets/test_popupreflows.xhtml",  
+      "toolkit/content/tests/widgets/window_menubar.xhtml",
+      "toolkit/modules/tests/chrome/test_bug544442_checkCert.xhtml",
+      "toolkit/profile/test/test_create_profile.xhtml",
+    ],
+    "rules": {
+      "object-shorthand": "off",
+      "consistent-return": "off",
+      "mozilla/consistent-if-bracing": "off",
+      "mozilla/no-compare-against-boolean-literals": "off",
+      "mozilla/no-useless-parameters": "off",
+      "mozilla/no-useless-removeEventListener": "off",
+      "mozilla/prefer-boolean-length-check": "off",
+      "mozilla/use-cc-etc": "off",
+      "mozilla/use-chromeutils-generateqi": "off",
+      "mozilla/use-chromeutils-import": "off",
+      "mozilla/use-default-preference-values": "off",
+      "mozilla/use-services": "off",
+      "no-caller": "off",
+      "no-else-return": "off",
+      "no-eval": "off",
+      "no-fallthrough": "off",
+      "no-irregular-whitespace": "off",
+      "no-lonely-if": "off",
+      "no-nested-ternary": "off",
+      "no-redeclare": "off",
+      "no-sequences": "off",
+      "no-shadow": "off",
+      "no-throw-literal": "off",
+      "no-undef": "off",
+      "no-unneeded-ternary": "off",
+      "no-unused-vars": "off",
+      "no-useless-concat": "off",
+      "no-useless-return": "off",
+    }
+  }, {
+    "files": [
       "accessible/**",
       "devtools/**",
       "dom/**",
       "docshell/**",
       "editor/libeditor/tests/**",
       "editor/spellchecker/tests/test_bug338427.html",
       "gfx/**",
       "image/test/browser/browser_image.js",

--- a/toolkit/components/aboutmemory/tests/chrome.ini
+++ b/toolkit/components/aboutmemory/tests/chrome.ini
@@ -3,29 +3,29 @@ skip-if = os == 'android'
 support-files =
   crash-dump-diff1.json
   crash-dump-diff2.json
   crash-dump-good.json
   memory-reports-bad.json
   memory-reports-diff1.json
   memory-reports-diff2.json
   memory-reports-good.json
-  remote.xul
+  remote.xhtml
 
-[test_aboutmemory.xul]
+[test_aboutmemory.xhtml]
 tags = clipboard
-[test_aboutmemory2.xul]
+[test_aboutmemory2.xhtml]
 tags = clipboard
-[test_aboutmemory3.xul]
+[test_aboutmemory3.xhtml]
 tags = clipboard
-[test_aboutmemory4.xul]
+[test_aboutmemory4.xhtml]
 tags = clipboard
-[test_aboutmemory5.xul]
+[test_aboutmemory5.xhtml]
 tags = clipboard
 skip-if = asan # Bug 1116230
-[test_aboutmemory6.xul]
-[test_aboutmemory7.xul]
+[test_aboutmemory6.xhtml]
+[test_aboutmemory7.xhtml]
 tags = clipboard
-[test_memoryReporters.xul]
-[test_memoryReporters2.xul]
-[test_sqliteMultiReporter.xul]
-[test_dumpGCAndCCLogsToFile.xul]
+[test_memoryReporters.xhtml]
+[test_memoryReporters2.xhtml]
+[test_sqliteMultiReporter.xhtml]
+[test_dumpGCAndCCLogsToFile.xhtml]
 skip-if = (verify && debug && (os == 'mac'))

rename from toolkit/components/aboutmemory/tests/remote.xul
rename to toolkit/components/aboutmemory/tests/remote.xhtml

rename from toolkit/components/aboutmemory/tests/test_aboutmemory.xul
rename to toolkit/components/aboutmemory/tests/test_aboutmemory.xhtml
--- a/toolkit/components/aboutmemory/tests/test_aboutmemory.xul
+++ b/toolkit/components/aboutmemory/tests/test_aboutmemory.xhtml
@@ -2,17 +2,17 @@
 <?xml-stylesheet type="text/css" href="chrome://global/skin"?>
 <?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
 <window title="about:memory"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
   <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
 
   <!-- This file uses fake memory reporters to test the presentation of memory
-       reports in about:memory.  test_memoryReporters.xul uses the real
+       reports in about:memory.  test_memoryReporters.xhtml uses the real
        memory reporters to test whether the memory reporters are producing
        sensible results. -->
 
   <!-- test results are displayed in the html:body -->
   <body xmlns="http://www.w3.org/1999/xhtml"></body>
 
   <!-- test code goes here -->
   <script type="application/javascript">

rename from toolkit/components/aboutmemory/tests/test_aboutmemory2.xul
rename to toolkit/components/aboutmemory/tests/test_aboutmemory2.xhtml

rename from toolkit/components/aboutmemory/tests/test_aboutmemory3.xul
rename to toolkit/components/aboutmemory/tests/test_aboutmemory3.xhtml

rename from toolkit/components/aboutmemory/tests/test_aboutmemory4.xul
rename to toolkit/components/aboutmemory/tests/test_aboutmemory4.xhtml

rename from toolkit/components/aboutmemory/tests/test_aboutmemory5.xul
rename to toolkit/components/aboutmemory/tests/test_aboutmemory5.xhtml
--- a/toolkit/components/aboutmemory/tests/test_aboutmemory5.xul
+++ b/toolkit/components/aboutmemory/tests/test_aboutmemory5.xhtml
@@ -37,17 +37,17 @@
 
   let prefs = [
     ["dom.ipc.processCount", 3],            // Allow up to 3 child processes
     ["memory.report_concurrency", 2]        // Cover more child handling cases
   ];
 
   SpecialPowers.pushPrefEnv({"set": prefs}, function() {
     for (let i = 0; i < numRemotes; i++) {
-      let w = remotes[i] = docShell.rootTreeItem.domWindow.open("remote.xul", "", "chrome");
+      let w = remotes[i] = docShell.rootTreeItem.domWindow.open("remote.xhtml", "", "chrome");
 
       w.addEventListener("load", function loadHandler() {
         w.removeEventListener("load", loadHandler);
         let remoteBrowser = w.document.getElementById("remote");
         let mm = remoteBrowser.messageManager;
         mm.addMessageListener("test:ready", function readyHandler() {
           mm.removeMessageListener("test:ready", readyHandler);
           numReady++;

rename from toolkit/components/aboutmemory/tests/test_aboutmemory6.xul
rename to toolkit/components/aboutmemory/tests/test_aboutmemory6.xhtml

rename from toolkit/components/aboutmemory/tests/test_aboutmemory7.xul
rename to toolkit/components/aboutmemory/tests/test_aboutmemory7.xhtml

rename from toolkit/components/aboutmemory/tests/test_dumpGCAndCCLogsToFile.xul
rename to toolkit/components/aboutmemory/tests/test_dumpGCAndCCLogsToFile.xhtml
--- a/toolkit/components/aboutmemory/tests/test_dumpGCAndCCLogsToFile.xul
+++ b/toolkit/components/aboutmemory/tests/test_dumpGCAndCCLogsToFile.xhtml
@@ -19,17 +19,17 @@
   let numReady = 0;
 
   // Create some remote processes, and set up message-passing so that
   // we know when each child is fully initialized.
   let remotes = [];
   SpecialPowers.pushPrefEnv({"set": [["dom.ipc.processCount", numRemotes]]},
 			    function() {
     for (let i = 0; i < numRemotes; i++) {
-      let w = remotes[i] = docShell.rootTreeItem.domWindow.open("remote.xul", "", "chrome");
+      let w = remotes[i] = docShell.rootTreeItem.domWindow.open("remote.xhtml", "", "chrome");
 
       w.addEventListener("load", function loadHandler() {
         w.removeEventListener("load", loadHandler);
         let remoteBrowser = w.document.getElementById("remote");
         let mm = remoteBrowser.messageManager;
         mm.addMessageListener("test:ready", function readyHandler() {
           mm.removeMessageListener("test:ready", readyHandler);
           numReady++;

rename from toolkit/components/aboutmemory/tests/test_memoryReporters.xul
rename to toolkit/components/aboutmemory/tests/test_memoryReporters.xhtml
--- a/toolkit/components/aboutmemory/tests/test_memoryReporters.xul
+++ b/toolkit/components/aboutmemory/tests/test_memoryReporters.xhtml
@@ -1,17 +1,17 @@
 <?xml version="1.0"?>
 <?xml-stylesheet type="text/css" href="chrome://global/skin"?>
 <?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
 <window title="Memory reporters"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
 
   <!-- This file tests (in a rough fashion) whether the memory reporters are
-       producing sensible results.  test_aboutmemory.xul tests the
+       producing sensible results.  test_aboutmemory.xhtml tests the
        presentation of memory reports in about:memory. -->
 
   <!-- test results are displayed in the html:body -->
   <body xmlns="http://www.w3.org/1999/xhtml">
   <!-- In bug 773533, <marquee> elements crashed the JS memory reporter -->
   <marquee>Marquee</marquee>
   </body>
 

rename from toolkit/components/aboutmemory/tests/test_memoryReporters2.xul
rename to toolkit/components/aboutmemory/tests/test_memoryReporters2.xhtml
--- a/toolkit/components/aboutmemory/tests/test_memoryReporters2.xul
+++ b/toolkit/components/aboutmemory/tests/test_memoryReporters2.xhtml
@@ -26,17 +26,17 @@
   const expectedNumRemotes = numToOpen + socketProcessRunning;
   let numReady = 0;
 
   // Create some remote processes, and set up message-passing so that
   // we know when each child is fully initialized.
   let remotes = [];
   SpecialPowers.pushPrefEnv({"set": [["dom.ipc.processCount", 3]]}, function() {
     for (let i = 0; i < numToOpen; i++) {
-      let w = remotes[i] = docShell.rootTreeItem.domWindow.open("remote.xul", "", "chrome");
+      let w = remotes[i] = docShell.rootTreeItem.domWindow.open("remote.xhtml", "", "chrome");
 
       w.addEventListener("load", function loadHandler() {
         w.removeEventListener("load", loadHandler);
         let remoteBrowser = w.document.getElementById("remote");
         let mm = remoteBrowser.messageManager;
         mm.addMessageListener("test:ready", function readyHandler() {
           mm.removeMessageListener("test:ready", readyHandler);
           numReady++;

rename from toolkit/components/aboutmemory/tests/test_sqliteMultiReporter.xul
rename to toolkit/components/aboutmemory/tests/test_sqliteMultiReporter.xhtml

--- a/toolkit/components/ctypes/tests/chrome/chrome.ini
+++ b/toolkit/components/ctypes/tests/chrome/chrome.ini
@@ -1,9 +1,9 @@
 [DEFAULT]
 skip-if = os == 'android'
 support-files =
   xpcshellTestHarnessAdaptor.js
   ctypes_worker.js
   ../unit/test_jsctypes.js
 
-[test_ctypes.xul]
+[test_ctypes.xhtml]
 skip-if = verify

rename from toolkit/components/ctypes/tests/chrome/test_ctypes.xul
rename to toolkit/components/ctypes/tests/chrome/test_ctypes.xhtml
--- a/toolkit/components/ctypes/tests/chrome/test_ctypes.xul
+++ b/toolkit/components/ctypes/tests/chrome/test_ctypes.xhtml
@@ -35,17 +35,17 @@
     }
 
     function getLocalDir(path) {
       let dir = Cc["@mozilla.org/file/directory_service;1"]
                   .getService(Ci.nsIProperties)
                   .get("CurWorkD", Ci.nsIFile);
       path = location.pathname;
       path = path.slice("content/".length,
-                                         -1 * "/test_ctypes.xul".length);
+                                         -1 * "/test_ctypes.xhtml".length);
       let components = path.split("/");
       for (let part in components) {
         dir.append(components[part]);
       }
       return dir;    
     }
 
     function setupLibs(path) {

--- a/toolkit/components/osfile/tests/mochi/chrome.ini
+++ b/toolkit/components/osfile/tests/mochi/chrome.ini
@@ -4,12 +4,12 @@ support-files =
   main_test_osfile_async.js
   worker_handler.js
   worker_test_osfile_comms.js
   worker_test_osfile_front.js
   worker_test_osfile_shared.js
   worker_test_osfile_unix.js
   worker_test_osfile_win.js
 
-[test_osfile_async.xul]
-[test_osfile_back.xul]
-[test_osfile_comms.xul]
-[test_osfile_front.xul]
+[test_osfile_async.xhtml]
+[test_osfile_back.xhtml]
+[test_osfile_comms.xhtml]
+[test_osfile_front.xhtml]

rename from toolkit/components/osfile/tests/mochi/test_osfile_async.xul
rename to toolkit/components/osfile/tests/mochi/test_osfile_async.xhtml

rename from toolkit/components/osfile/tests/mochi/test_osfile_back.xul
rename to toolkit/components/osfile/tests/mochi/test_osfile_back.xhtml

rename from toolkit/components/osfile/tests/mochi/test_osfile_comms.xul
rename to toolkit/components/osfile/tests/mochi/test_osfile_comms.xhtml
--- a/toolkit/components/osfile/tests/mochi/test_osfile_comms.xul
+++ b/toolkit/components/osfile/tests/mochi/test_osfile_comms.xhtml
@@ -14,17 +14,17 @@
 
 "use strict";
 
 let worker;
 
 SpecialPowers.pushPrefEnv({"set": [["security.allow_eval_with_system_principal",
                                     true]]});
 let test = function test() {
-  SimpleTest.info("test_osfile_comms.xul: Starting test");
+  SimpleTest.info("test_osfile_comms.xhtml: Starting test");
   ChromeUtils.import("resource://gre/modules/ctypes.jsm", window);
   ChromeUtils.import("resource://gre/modules/osfile.jsm", window);
   worker = new ChromeWorker("worker_test_osfile_comms.js");
   SimpleTest.waitForExplicitFinish();
   try {
     worker.onerror = function onerror(error) {
       SimpleTest.ok(false, "received error "+error);
     }
@@ -44,25 +44,25 @@ let test = function test() {
         return;
       case "info":
         SimpleTest.info(msg.data.description);
         return;
       case "finish":
         SimpleTest.finish();
         return;
       case "value":
-        SimpleTest.ok(true, "test_osfile_comms.xul: Received value " + JSON.stringify(msg.data.value));
+        SimpleTest.ok(true, "test_osfile_comms.xhtml: Received value " + JSON.stringify(msg.data.value));
         let type = eval(msg.data.typename);
         let check = eval(msg.data.check);
         let value = msg.data.value;
         let deserialized = type.fromMsg(value);
         check(deserialized, "Main thread test: ");
        return;
       default:
-        SimpleTest.ok(false, "test_osfile_comms.xul: wrong message "+JSON.stringify(msg.data));
+        SimpleTest.ok(false, "test_osfile_comms.xhtml: wrong message "+JSON.stringify(msg.data));
         return;
       }
     };
     worker.postMessage(0)
     ok(true, "Worker launched");
   } catch(x) {
     // As we have set |waitForExplicitFinish|, we add this fallback
     // in case of uncaught error, to ensure that the test does not

rename from toolkit/components/osfile/tests/mochi/test_osfile_front.xul
rename to toolkit/components/osfile/tests/mochi/test_osfile_front.xhtml
--- a/toolkit/components/osfile/tests/mochi/test_osfile_front.xul
+++ b/toolkit/components/osfile/tests/mochi/test_osfile_front.xhtml
@@ -13,27 +13,27 @@
           src="worker_handler.js"/>
   <script type="application/javascript">
   <![CDATA[
 
 let worker;
 let main = this;
 
 function test() {
-  info("test_osfile_front.xul: Starting test");
+  info("test_osfile_front.xhtml: Starting test");
 
   // Test the OS.File worker
 
   worker = new ChromeWorker("worker_test_osfile_front.js");
   SimpleTest.waitForExplicitFinish();
-  info("test_osfile_front.xul: Chrome worker created");
+  info("test_osfile_front.xhtml: Chrome worker created");
   dump("MAIN: go\n");
   worker_handler(worker);
   worker.postMessage(0);
-  ok(true, "test_osfile_front.xul: Test in progress");
+  ok(true, "test_osfile_front.xhtml: Test in progress");
 };
 ]]>
   </script>
 
   <body xmlns="http://www.w3.org/1999/xhtml">
     <p id="display"></p>
     <div id="content" style="display:none;"></div>
     <pre id="test"></pre>

--- a/toolkit/components/osfile/tests/mochi/worker_test_osfile_front.js
+++ b/toolkit/components/osfile/tests/mochi/worker_test_osfile_front.js
@@ -652,17 +652,17 @@ function test_path() {
 function test_exists_file() {
   let file_name = OS.Path.join(
     "chrome",
     "toolkit",
     "components",
     "osfile",
     "tests",
     "mochi",
-    "test_osfile_front.xul"
+    "test_osfile_front.xhtml"
   );
   info("test_exists_file: starting");
   ok(
     OS.File.exists(file_name),
     "test_exists_file: file exists (OS.File.exists)"
   );
   ok(
     !OS.File.exists(file_name + ".tmp"),

rename from toolkit/components/places/tests/chrome/browser_disableglobalhistory.xul
rename to toolkit/components/places/tests/chrome/browser_disableglobalhistory.xhtml
--- a/toolkit/components/places/tests/chrome/browser_disableglobalhistory.xul
+++ b/toolkit/components/places/tests/chrome/browser_disableglobalhistory.xhtml
@@ -14,16 +14,17 @@
 
   <script type="text/javascript">
 
   Cu.import("resource://testing-common/ContentTask.jsm");
   ContentTask.setTestScope(window.arguments[0].wrappedJSObject);
 
   function expectUseGlobalHistory(id, expected) {
     let browser = document.getElementById(id);
+    /* eslint-disable-next-line no-shadow */
     return ContentTask.spawn(browser, {id, expected}, function({id, expected}) {
       Assert.equal(docShell.useGlobalHistory, expected,
                    "Got the right useGlobalHistory state in the docShell of " + id);
     });
   }
 
   async function run_test() {
     await expectUseGlobalHistory("inprocess_disabled", false);

--- a/toolkit/components/places/tests/chrome/chrome.ini
+++ b/toolkit/components/places/tests/chrome/chrome.ini
@@ -1,7 +1,7 @@
 [DEFAULT]
 support-files = head.js
 
-[test_371798.xul]
-[test_favicon_annotations.xul]
-[test_browser_disableglobalhistory.xul]
-support-files = browser_disableglobalhistory.xul
+[test_371798.xhtml]
+[test_favicon_annotations.xhtml]
+[test_browser_disableglobalhistory.xhtml]
+support-files = browser_disableglobalhistory.xhtml

rename from toolkit/components/places/tests/chrome/test_371798.xul
rename to toolkit/components/places/tests/chrome/test_371798.xhtml

rename from toolkit/components/places/tests/chrome/test_browser_disableglobalhistory.xul
rename to toolkit/components/places/tests/chrome/test_browser_disableglobalhistory.xhtml
--- a/toolkit/components/places/tests/chrome/test_browser_disableglobalhistory.xul
+++ b/toolkit/components/places/tests/chrome/test_browser_disableglobalhistory.xhtml
@@ -9,17 +9,17 @@
 
   <!-- test results are displayed in the html:body -->
   <body xmlns="http://www.w3.org/1999/xhtml">
   </body>
 
   <script type="text/javascript">
   SimpleTest.waitForExplicitFinish();
 
-  let w = docShell.rootTreeItem.domWindow.openDialog('browser_disableglobalhistory.xul', '_blank', 'chrome,resizable=yes,width=400,height=600', window);
+  let w = docShell.rootTreeItem.domWindow.openDialog('browser_disableglobalhistory.xhtml', '_blank', 'chrome,resizable=yes,width=400,height=600', window);
 
   function done() {
     w.close();
     SimpleTest.finish();
   }
   </script>
 
 </window>

rename from toolkit/components/places/tests/chrome/test_favicon_annotations.xul
rename to toolkit/components/places/tests/chrome/test_favicon_annotations.xhtml

--- a/toolkit/components/workerloader/tests/chrome.ini
+++ b/toolkit/components/workerloader/tests/chrome.ini
@@ -7,9 +7,9 @@ support-files =
   moduleE-throws-during-require.js
   moduleF-syntax-error.js
   moduleG-throws-later.js
   moduleH-module-dot-exports.js
   utils_mainthread.js
   utils_worker.js
   worker_test_loading.js
 
-[test_loading.xul]
+[test_loading.xhtml]

rename from toolkit/components/workerloader/tests/test_loading.xul
rename to toolkit/components/workerloader/tests/test_loading.xhtml

--- a/toolkit/components/xulstore/tests/chrome/chrome.ini
+++ b/toolkit/components/xulstore/tests/chrome/chrome.ini
@@ -1,5 +1,5 @@
 [DEFAULT]
 support-files =
-  window_persistence.xul
+  window_persistence.xhtml
 
-[test_persistence.xul]
+[test_persistence.xhtml]

rename from toolkit/components/xulstore/tests/chrome/test_persistence.xul
rename to toolkit/components/xulstore/tests/chrome/test_persistence.xhtml
--- a/toolkit/components/xulstore/tests/chrome/test_persistence.xul
+++ b/toolkit/components/xulstore/tests/chrome/test_persistence.xhtml
@@ -6,21 +6,21 @@
         onload="runTest()"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
 
   <script>
     SimpleTest.waitForExplicitFinish();
     function runTest() {
-      window.openDialog("window_persistence.xul", "_blank", "chrome,noopener", true, window);
+      window.openDialog("window_persistence.xhtml", "_blank", "chrome,noopener", true, window);
     }
 
     function windowOpened() {
-      window.openDialog("window_persistence.xul", "_blank", "chrome,noopener", false, window);
+      window.openDialog("window_persistence.xhtml", "_blank", "chrome,noopener", false, window);
     }
 
     function testDone() {
       SimpleTest.finish();
     }
   </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">

rename from toolkit/components/xulstore/tests/chrome/window_persistence.xul
rename to toolkit/components/xulstore/tests/chrome/window_persistence.xhtml
--- a/toolkit/components/xulstore/tests/chrome/window_persistence.xul
+++ b/toolkit/components/xulstore/tests/chrome/window_persistence.xhtml
@@ -10,17 +10,17 @@
 <button id="button1" label="Button1" persist="value"/>
 <button id="button2" label="Button2" value="Normal" persist="value"/>
 
 <script>
 <![CDATA[
 
 const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
 const XULStore = Services.xulStore;
-let URI = "chrome://mochitests/content/chrome/toolkit/components/xulstore/tests/chrome/window_persistence.xul";
+let URI = "chrome://mochitests/content/chrome/toolkit/components/xulstore/tests/chrome/window_persistence.xhtml";
 
 function opened()
 {
   runTest();
 }
 
 function runTest()
 {

rename from toolkit/content/tests/chrome/bug263683_window.xul
rename to toolkit/content/tests/chrome/bug263683_window.xhtml

rename from toolkit/content/tests/chrome/bug304188_window.xul
rename to toolkit/content/tests/chrome/bug304188_window.xhtml

rename from toolkit/content/tests/chrome/bug331215_window.xul
rename to toolkit/content/tests/chrome/bug331215_window.xhtml

rename from toolkit/content/tests/chrome/bug360437_window.xul
rename to toolkit/content/tests/chrome/bug360437_window.xhtml

rename from toolkit/content/tests/chrome/bug366992_window.xul
rename to toolkit/content/tests/chrome/bug366992_window.xhtml

rename from toolkit/content/tests/chrome/bug409624_window.xul
rename to toolkit/content/tests/chrome/bug409624_window.xhtml

rename from toolkit/content/tests/chrome/bug429723_window.xul
rename to toolkit/content/tests/chrome/bug429723_window.xhtml

rename from toolkit/content/tests/chrome/bug451540_window.xul
rename to toolkit/content/tests/chrome/bug451540_window.xhtml

rename from toolkit/content/tests/chrome/bug624329_window.xul
rename to toolkit/content/tests/chrome/bug624329_window.xhtml

--- a/toolkit/content/tests/chrome/chrome.ini
+++ b/toolkit/content/tests/chrome/chrome.ini
@@ -1,205 +1,205 @@
 [DEFAULT]
 skip-if = os == 'android'
 support-files =
   ../widgets/popup_shared.js
   ../widgets/tree_shared.js
   RegisterUnregisterChrome.js
-  bug263683_window.xul
-  bug304188_window.xul
-  bug331215_window.xul
-  bug360437_window.xul
-  bug366992_window.xul
-  bug409624_window.xul
-  bug429723_window.xul
-  bug624329_window.xul
-  dialog_dialogfocus.xul
-  dialog_dialogfocus2.xul
+  bug263683_window.xhtml
+  bug304188_window.xhtml
+  bug331215_window.xhtml
+  bug360437_window.xhtml
+  bug366992_window.xhtml
+  bug409624_window.xhtml
+  bug429723_window.xhtml
+  bug624329_window.xhtml
+  dialog_dialogfocus.xhtml
+  dialog_dialogfocus2.xhtml
   file_empty.xhtml
-  file_edit_contextmenu.xul
+  file_edit_contextmenu.xhtml
   file_about_networking_wsh.py
   file_autocomplete_with_composition.js
   file_editor_with_autocomplete.js
-  findbar_entireword_window.xul
-  findbar_events_window.xul
-  findbar_window.xul
-  frame_popup_anchor.xul
-  frame_popupremoving_frame.xul
-  frame_subframe_origin_subframe1.xul
-  frame_subframe_origin_subframe2.xul
-  popup_childframe_node.xul
+  findbar_entireword_window.xhtml
+  findbar_events_window.xhtml
+  findbar_window.xhtml
+  frame_popup_anchor.xhtml
+  frame_popupremoving_frame.xhtml
+  frame_subframe_origin_subframe1.xhtml
+  frame_subframe_origin_subframe2.xhtml
+  popup_childframe_node.xhtml
   popup_trigger.js
   sample_entireword_latin1.html
-  window_browser_drop.xul
-  window_keys.xul
-  window_largemenu.xul
-  window_panel.xul
-  window_panel_anchoradjust.xul
-  window_popup_anchor.xul
-  window_popup_anchoratrect.xul
-  window_popup_attribute.xul
-  window_popup_button.xul
-  window_popup_preventdefault_chrome.xul
-  window_preferences.xul
-  window_preferences2.xul
-  window_preferences3.xul
-  window_preferences_commandretarget.xul
-  window_screenPosSize.xul
-  window_showcaret.xul
-  window_subframe_origin.xul
-  window_titlebar.xul
-  window_tooltip.xul
+  window_browser_drop.xhtml
+  window_keys.xhtml
+  window_largemenu.xhtml
+  window_panel.xhtml
+  window_panel_anchoradjust.xhtml
+  window_popup_anchor.xhtml
+  window_popup_anchoratrect.xhtml
+  window_popup_attribute.xhtml
+  window_popup_button.xhtml
+  window_popup_preventdefault_chrome.xhtml
+  window_preferences.xhtml
+  window_preferences2.xhtml
+  window_preferences3.xhtml
+  window_preferences_commandretarget.xhtml
+  window_screenPosSize.xhtml
+  window_showcaret.xhtml
+  window_subframe_origin.xhtml
+  window_titlebar.xhtml
+  window_tooltip.xhtml
   xul_selectcontrol.js
   rtlchrome/rtl.css
   rtlchrome/rtl.dtd
   rtlchrome/rtl.manifest
   rtltest/righttoleft.manifest
-  rtltest/content/dirtest.xul
+  rtltest/content/dirtest.xhtml
 
 [test_about_networking.html]
-[test_arrowpanel.xul]
+[test_arrowpanel.xhtml]
 skip-if = (verify && (os == 'win')) || (debug && (os == 'win') && (bits == 32)) # Bug 1546256
-[test_autocomplete2.xul]
-[test_autocomplete3.xul]
-[test_autocomplete4.xul]
-[test_autocomplete5.xul]
-[test_autocomplete_emphasis.xul]
+[test_autocomplete2.xhtml]
+[test_autocomplete3.xhtml]
+[test_autocomplete4.xhtml]
+[test_autocomplete5.xhtml]
+[test_autocomplete_emphasis.xhtml]
 [test_autocomplete_with_composition_on_input.html]
-[test_autocomplete_placehold_last_complete.xul]
-[test_browser_drop.xul]
+[test_autocomplete_placehold_last_complete.xhtml]
+[test_browser_drop.xhtml]
 tags = clipboard
-[test_bug263683.xul]
+[test_bug263683.xhtml]
 skip-if = debug && (os == 'win' || os == 'linux')
-[test_bug304188.xul]
+[test_bug304188.xhtml]
 skip-if = webrender
-[test_bug331215.xul]
+[test_bug331215.xhtml]
 skip-if = webrender || (os == 'win' && debug) || (os == 'mac' && debug) #Bug 1339326 #Bug 1582327
-[test_bug360220.xul]
-[test_bug360437.xul]
+[test_bug360220.xhtml]
+[test_bug360437.xhtml]
 skip-if = os == 'linux' # Bug 1264604
-[test_bug365773.xul]
-[test_bug366992.xul]
-[test_bug382990.xul]
-[test_bug409624.xul]
-[test_bug418874.xul]
-[test_bug429723.xul]
-[test_bug437844.xul]
+[test_bug365773.xhtml]
+[test_bug366992.xhtml]
+[test_bug382990.xhtml]
+[test_bug409624.xhtml]
+[test_bug418874.xhtml]
+[test_bug429723.xhtml]
+[test_bug437844.xhtml]
 skip-if = (verify && debug && (os == 'mac' || os == 'win'))
-[test_bug451540.xul]
-support-files = bug451540_window.xul
-[test_bug457632.xul]
-[test_bug460942.xul]
-[test_bug471776.xul]
-[test_bug509732.xul]
-[test_bug557987.xul]
-[test_bug562554.xul]
-[test_bug624329.xul]
-[test_bug792324.xul]
-[test_bug1048178.xul]
+[test_bug451540.xhtml]
+support-files = bug451540_window.xhtml
+[test_bug457632.xhtml]
+[test_bug460942.xhtml]
+[test_bug471776.xhtml]
+[test_bug509732.xhtml]
+[test_bug557987.xhtml]
+[test_bug562554.xhtml]
+[test_bug624329.xhtml]
+[test_bug792324.xhtml]
+[test_bug1048178.xhtml]
 skip-if = toolkit == "cocoa"
-[test_button.xul]
-[test_closemenu_attribute.xul]
-[test_contextmenu_list.xul]
-[test_custom_element_base.xul]
-[test_custom_element_delay_connection.xul]
+[test_button.xhtml]
+[test_closemenu_attribute.xhtml]
+[test_contextmenu_list.xhtml]
+[test_custom_element_base.xhtml]
+[test_custom_element_delay_connection.xhtml]
 [test_custom_element_parts.html]
-[test_deck.xul]
-[test_dialogfocus.xul]
+[test_deck.xhtml]
+[test_dialogfocus.xhtml]
 [test_edit_contextmenu.html]
 [test_editor_for_input_with_autocomplete.html]
-[test_findbar.xul]
+[test_findbar.xhtml]
 tags = clipboard
 skip-if = os == 'mac' && os_version == '10.14' # macosx1014 due to 1550078
-[test_findbar_entireword.xul]
-[test_findbar_events.xul]
-[test_frames.xul]
-[test_hiddenitems.xul]
-[test_hiddenpaging.xul]
-[test_keys.xul]
-[test_labelcontrol.xul]
+[test_findbar_entireword.xhtml]
+[test_findbar_events.xhtml]
+[test_frames.xhtml]
+[test_hiddenitems.xhtml]
+[test_hiddenpaging.xhtml]
+[test_keys.xhtml]
+[test_labelcontrol.xhtml]
 [test_largemenu.html]
 skip-if = os == 'linux' && !debug # Bug 1207174
-[test_maximized_persist.xul]
-support-files = window_maximized_persist.xul
+[test_maximized_persist.xhtml]
+support-files = window_maximized_persist.xhtml
 [test_navigate_persist.html]
 support-files = window_navigate_persist.html
-[test_menu.xul]
-[test_menu_withcapture.xul]
-[test_menu_hide.xul]
-[test_menuchecks.xul]
-[test_menuitem_blink.xul]
-[test_menuitem_commands.xul]
-[test_menulist.xul]
-[test_menulist_keynav.xul]
-[test_menulist_null_value.xul]
-[test_menulist_paging.xul]
-[test_menulist_position.xul]
-[test_mousescroll.xul]
-[test_mozinputbox_dictionary.xul]
-[test_notificationbox.xul]
+[test_menu.xhtml]
+[test_menu_withcapture.xhtml]
+[test_menu_hide.xhtml]
+[test_menuchecks.xhtml]
+[test_menuitem_blink.xhtml]
+[test_menuitem_commands.xhtml]
+[test_menulist.xhtml]
+[test_menulist_keynav.xhtml]
+[test_menulist_null_value.xhtml]
+[test_menulist_paging.xhtml]
+[test_menulist_position.xhtml]
+[test_mousescroll.xhtml]
+[test_mozinputbox_dictionary.xhtml]
+[test_notificationbox.xhtml]
 skip-if = (os == 'linux' && debug) || (os == 'win') # Bug 1429649
-[test_panel.xul]
+[test_panel.xhtml]
 skip-if = os == 'mac' && os_version == '10.14' # macosx1014 due to 1550078
-[test_panel_anchoradjust.xul]
-[test_panelfrommenu.xul]
-[test_popup_anchor.xul]
-[test_popup_anchoratrect.xul]
+[test_panel_anchoradjust.xhtml]
+[test_panelfrommenu.xhtml]
+[test_popup_anchor.xhtml]
+[test_popup_anchoratrect.xhtml]
 skip-if = os == 'linux' # 1167694
-[test_popup_attribute.xul]
+[test_popup_attribute.xhtml]
 skip-if = os == 'linux' && asan || (os == 'mac' && debug) # Bug 1281360, 1582610
-[test_popup_button.xul]
+[test_popup_button.xhtml]
 skip-if = os == 'linux' && asan || (os == 'mac' && debug) # Bug 1281360, 1582610
-[test_popup_coords.xul]
-[test_popup_keys.xul]
-[test_popup_moveToAnchor.xul]
-[test_popup_preventdefault.xul]
-[test_popup_preventdefault_chrome.xul]
-[test_popup_recreate.xul]
-[test_popup_scaled.xul]
-[test_popup_tree.xul]
-[test_popuphidden.xul]
-[test_popupincontent.xul]
+[test_popup_coords.xhtml]
+[test_popup_keys.xhtml]
+[test_popup_moveToAnchor.xhtml]
+[test_popup_preventdefault.xhtml]
+[test_popup_preventdefault_chrome.xhtml]
+[test_popup_recreate.xhtml]
+[test_popup_scaled.xhtml]
+[test_popup_tree.xhtml]
+[test_popuphidden.xhtml]
+[test_popupincontent.xhtml]
 skip-if = (verify && (os == 'win'))
-[test_popupremoving.xul]
-[test_popupremoving_frame.xul]
-[test_position.xul]
-[test_preferences.xul]
-[test_preferences_beforeaccept.xul]
-support-files = window_preferences_beforeaccept.xul
-[test_preferences_onsyncfrompreference.xul]
-support-files = window_preferences_onsyncfrompreference.xul
-[test_props.xul]
-[test_radio.xul]
-[test_richlistbox.xul]
-[test_righttoleft.xul]
-[test_screenPersistence.xul]
-[test_scrollbar.xul]
-[test_showcaret.xul]
-[test_subframe_origin.xul]
-[test_tabbox.xul]
-[test_tabindex.xul]
-[test_textbox_search.xul]
-[test_titlebar.xul]
+[test_popupremoving.xhtml]
+[test_popupremoving_frame.xhtml]
+[test_position.xhtml]
+[test_preferences.xhtml]
+[test_preferences_beforeaccept.xhtml]
+support-files = window_preferences_beforeaccept.xhtml
+[test_preferences_onsyncfrompreference.xhtml]
+support-files = window_preferences_onsyncfrompreference.xhtml
+[test_props.xhtml]
+[test_radio.xhtml]
+[test_richlistbox.xhtml]
+[test_righttoleft.xhtml]
+[test_screenPersistence.xhtml]
+[test_scrollbar.xhtml]
+[test_showcaret.xhtml]
+[test_subframe_origin.xhtml]
+[test_tabbox.xhtml]
+[test_tabindex.xhtml]
+[test_textbox_search.xhtml]
+[test_titlebar.xhtml]
 skip-if = os == "linux" || (os == 'mac' && os_version == '10.14') # macosx1014 due to 1550078
-[test_tooltip.xul]
+[test_tooltip.xhtml]
 skip-if = (os == 'mac' || os == 'win') # Bug 1141245, frequent timeouts on OSX 10.14, Windows
-[test_tooltip_noautohide.xul]
-[test_tree.xul]
-[test_tree_hier.xul]
-[test_tree_single.xul]
-[test_tree_view.xul]
-[test_window_intrinsic_size.xul]
-support-files = window_intrinsic_size.xul
-# test_panel_focus.xul won't work if the Full Keyboard Access preference is set to
+[test_tooltip_noautohide.xhtml]
+[test_tree.xhtml]
+[test_tree_hier.xhtml]
+[test_tree_single.xhtml]
+[test_tree_view.xhtml]
+[test_window_intrinsic_size.xhtml]
+support-files = window_intrinsic_size.xhtml
+# test_panel_focus.xhtml won't work if the Full Keyboard Access preference is set to
 # textboxes and lists only, so skip this test on Mac
-[test_panel_focus.xul]
-support-files = window_panel_focus.xul
+[test_panel_focus.xhtml]
+support-files = window_panel_focus.xhtml
 skip-if = toolkit == "cocoa"
-[test_chromemargin.xul]
-support-files = window_chromemargin.xul
+[test_chromemargin.xhtml]
+support-files = window_chromemargin.xhtml
 skip-if = toolkit == "cocoa"
-[test_autocomplete_mac_caret.xul]
+[test_autocomplete_mac_caret.xhtml]
 skip-if = toolkit != "cocoa"
-[test_cursorsnap.xul]
+[test_cursorsnap.xhtml]
 disabled =
 #skip-if = os != "win"
-support-files = window_cursorsnap_dialog.xul window_cursorsnap_wizard.xul
+support-files = window_cursorsnap_dialog.xhtml window_cursorsnap_wizard.xhtml

rename from toolkit/content/tests/chrome/dialog_dialogfocus.xul
rename to toolkit/content/tests/chrome/dialog_dialogfocus.xhtml

rename from toolkit/content/tests/chrome/dialog_dialogfocus2.xul
rename to toolkit/content/tests/chrome/dialog_dialogfocus2.xhtml

rename from toolkit/content/tests/chrome/file_edit_contextmenu.xul
rename to toolkit/content/tests/chrome/file_edit_contextmenu.xhtml

rename from toolkit/content/tests/chrome/findbar_entireword_window.xul
rename to toolkit/content/tests/chrome/findbar_entireword_window.xhtml

rename from toolkit/content/tests/chrome/findbar_events_window.xul
rename to toolkit/content/tests/chrome/findbar_events_window.xhtml

rename from toolkit/content/tests/chrome/findbar_window.xul
rename to toolkit/content/tests/chrome/findbar_window.xhtml

rename from toolkit/content/tests/chrome/frame_popup_anchor.xul
rename to toolkit/content/tests/chrome/frame_popup_anchor.xhtml

rename from toolkit/content/tests/chrome/frame_popupremoving_frame.xul
rename to toolkit/content/tests/chrome/frame_popupremoving_frame.xhtml

rename from toolkit/content/tests/chrome/frame_subframe_origin_subframe1.xul
rename to toolkit/content/tests/chrome/frame_subframe_origin_subframe1.xhtml
--- a/toolkit/content/tests/chrome/frame_subframe_origin_subframe1.xul
+++ b/toolkit/content/tests/chrome/frame_subframe_origin_subframe1.xhtml
@@ -7,17 +7,17 @@
 <window id="frame1"
         style="background-color:green;"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
 
 <spacer height="10px"/>
 <iframe
   style="margin:10px; min-height:170px; max-width:200px; max-height:200px; border:solid 1px white;"
-  src="frame_subframe_origin_subframe2.xul"></iframe>
+  src="frame_subframe_origin_subframe2.xhtml"></iframe>
 <spacer height="3px"/>
 <caption id="cap1" style="min-width:200px; max-width:200px; background-color:white;" label=""/>
 <script class="testbody" type="application/javascript">
 
 // Fire a mouse move event aimed at this window, and check to be
 // sure the client coords translate from widget to the dom correctly.
 
 function runTests()

rename from toolkit/content/tests/chrome/frame_subframe_origin_subframe2.xul
rename to toolkit/content/tests/chrome/frame_subframe_origin_subframe2.xhtml

rename from toolkit/content/tests/chrome/popup_childframe_node.xul
rename to toolkit/content/tests/chrome/popup_childframe_node.xhtml

rename from toolkit/content/tests/chrome/rtltest/content/dirtest.xul
rename to toolkit/content/tests/chrome/rtltest/content/dirtest.xhtml

rename from toolkit/content/tests/chrome/test_arrowpanel.xul
rename to toolkit/content/tests/chrome/test_arrowpanel.xhtml

rename from toolkit/content/tests/chrome/test_autocomplete2.xul
rename to toolkit/content/tests/chrome/test_autocomplete2.xhtml

rename from toolkit/content/tests/chrome/test_autocomplete3.xul
rename to toolkit/content/tests/chrome/test_autocomplete3.xhtml

rename from toolkit/content/tests/chrome/test_autocomplete4.xul
rename to toolkit/content/tests/chrome/test_autocomplete4.xhtml

rename from toolkit/content/tests/chrome/test_autocomplete5.xul
rename to toolkit/content/tests/chrome/test_autocomplete5.xhtml

rename from toolkit/content/tests/chrome/test_autocomplete_emphasis.xul
rename to toolkit/content/tests/chrome/test_autocomplete_emphasis.xhtml

rename from toolkit/content/tests/chrome/test_autocomplete_mac_caret.xul
rename to toolkit/content/tests/chrome/test_autocomplete_mac_caret.xhtml

rename from toolkit/content/tests/chrome/test_autocomplete_placehold_last_complete.xul
rename to toolkit/content/tests/chrome/test_autocomplete_placehold_last_complete.xhtml

rename from toolkit/content/tests/chrome/test_browser_drop.xul
rename to toolkit/content/tests/chrome/test_browser_drop.xhtml
--- a/toolkit/content/tests/chrome/test_browser_drop.xul
+++ b/toolkit/content/tests/chrome/test_browser_drop.xhtml
@@ -7,17 +7,17 @@
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
 
         <script><![CDATA[
 SimpleTest.waitForExplicitFinish();
 function runTest() {
   add_task(async function() {
-    let win = docShell.rootTreeItem.domWindow.openDialog("window_browser_drop.xul", "_blank", "chrome,width=200,height=200", window);
+    let win = docShell.rootTreeItem.domWindow.openDialog("window_browser_drop.xhtml", "_blank", "chrome,width=200,height=200", window);
     await SimpleTest.promiseFocus(win);
     for (let browserType of ["content", "remote-content"]) {
       await win.dropLinksOnBrowser(win.document.getElementById(browserType + "child"), browserType);
     }
     await win.dropLinksOnBrowser(win.document.getElementById("chromechild"), "chrome");
   });
 }
 //]]>

rename from toolkit/content/tests/chrome/test_bug1048178.xul
rename to toolkit/content/tests/chrome/test_bug1048178.xhtml

rename from toolkit/content/tests/chrome/test_bug263683.xul
rename to toolkit/content/tests/chrome/test_bug263683.xhtml
--- a/toolkit/content/tests/chrome/test_bug263683.xul
+++ b/toolkit/content/tests/chrome/test_bug263683.xhtml
@@ -25,15 +25,15 @@ https://bugzilla.mozilla.org/show_bug.cg
     </pre>
   </body>
 
   <script class="testbody" type="application/javascript">
     <![CDATA[
 
       /** Test for Bug 263683 **/
       SimpleTest.waitForExplicitFinish();
-      window.openDialog("bug263683_window.xul", "263683test",
+      window.openDialog("bug263683_window.xhtml", "263683test",
                         "chrome,width=600,height=600,noopener", window);
 
     ]]>
   </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_bug304188.xul
rename to toolkit/content/tests/chrome/test_bug304188.xhtml
--- a/toolkit/content/tests/chrome/test_bug304188.xul
+++ b/toolkit/content/tests/chrome/test_bug304188.xhtml
@@ -23,15 +23,15 @@ https://bugzilla.mozilla.org/show_bug.cg
 </pre>
 </body>
 
 <script class="testbody" type="application/javascript">
 <![CDATA[
 
 /** Test for Bug 304188 **/
 SimpleTest.waitForExplicitFinish();
-window.openDialog("bug304188_window.xul", "findbartest", 
+window.openDialog("bug304188_window.xhtml", "findbartest", 
                   "chrome,width=600,height=600,noopener", window);
 
 ]]>
 </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_bug331215.xul
rename to toolkit/content/tests/chrome/test_bug331215.xhtml
--- a/toolkit/content/tests/chrome/test_bug331215.xul
+++ b/toolkit/content/tests/chrome/test_bug331215.xhtml
@@ -24,15 +24,15 @@ https://bugzilla.mozilla.org/show_bug.cg
 </body>
 
 <script class="testbody" type="application/javascript">
 <![CDATA[
 
 /** Test for Bug 331215 **/
 
 SimpleTest.waitForExplicitFinish();
-window.openDialog("bug331215_window.xul", "331215test", 
+window.openDialog("bug331215_window.xhtml", "331215test", 
                   "chrome,width=600,height=600,noopener", window);
 
 ]]>
 </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_bug360220.xul
rename to toolkit/content/tests/chrome/test_bug360220.xhtml

rename from toolkit/content/tests/chrome/test_bug360437.xul
rename to toolkit/content/tests/chrome/test_bug360437.xhtml
--- a/toolkit/content/tests/chrome/test_bug360437.xul
+++ b/toolkit/content/tests/chrome/test_bug360437.xhtml
@@ -23,17 +23,17 @@ https://bugzilla.mozilla.org/show_bug.cg
 </pre>
 </body>
 
 <script class="testbody" type="application/javascript">
 <![CDATA[
 
 /** Test for Bug 360437 **/
 SimpleTest.waitForExplicitFinish();
-window.openDialog("bug360437_window.xul", "360437test", 
+window.openDialog("bug360437_window.xhtml", "360437test", 
                   "chrome,width=600,height=600,noopener", window);
 
 
 
 
 ]]>
 </script>
 

rename from toolkit/content/tests/chrome/test_bug365773.xul
rename to toolkit/content/tests/chrome/test_bug365773.xhtml

rename from toolkit/content/tests/chrome/test_bug366992.xul
rename to toolkit/content/tests/chrome/test_bug366992.xhtml
--- a/toolkit/content/tests/chrome/test_bug366992.xul
+++ b/toolkit/content/tests/chrome/test_bug366992.xhtml
@@ -23,17 +23,17 @@ https://bugzilla.mozilla.org/show_bug.cg
 </pre>
 </body>
 
 <script class="testbody" type="application/javascript">
 <![CDATA[
 
 /** Test for Bug 366992 **/
 SimpleTest.waitForExplicitFinish();
-window.openDialog("bug366992_window.xul", "findbartest", 
+window.openDialog("bug366992_window.xhtml", "findbartest", 
                   "chrome,width=600,height=600,noopener", window);
 
 
 
 
 ]]>
 </script>
 

rename from toolkit/content/tests/chrome/test_bug382990.xul
rename to toolkit/content/tests/chrome/test_bug382990.xhtml

rename from toolkit/content/tests/chrome/test_bug409624.xul
rename to toolkit/content/tests/chrome/test_bug409624.xhtml
--- a/toolkit/content/tests/chrome/test_bug409624.xul
+++ b/toolkit/content/tests/chrome/test_bug409624.xhtml
@@ -24,15 +24,15 @@ https://bugzilla.mozilla.org/show_bug.cg
     </pre>
   </body>
 
   <script class="testbody" type="application/javascript">
     <![CDATA[
 
       /** Test for Bug 409624 **/
       SimpleTest.waitForExplicitFinish();
-      window.openDialog("bug409624_window.xul", "409624test",
+      window.openDialog("bug409624_window.xhtml", "409624test",
                         "chrome,width=600,height=600,noopener", window);
 
     ]]>
   </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_bug418874.xul
rename to toolkit/content/tests/chrome/test_bug418874.xhtml

rename from toolkit/content/tests/chrome/test_bug429723.xul
rename to toolkit/content/tests/chrome/test_bug429723.xhtml
--- a/toolkit/content/tests/chrome/test_bug429723.xul
+++ b/toolkit/content/tests/chrome/test_bug429723.xhtml
@@ -24,15 +24,15 @@ https://bugzilla.mozilla.org/show_bug.cg
 </pre>
 </body>
 
 <script class="testbody" type="application/javascript">
 <![CDATA[
 
 /** Test for Bug 429723 **/
 SimpleTest.waitForExplicitFinish();
-window.openDialog("bug429723_window.xul", "429723test", 
+window.openDialog("bug429723_window.xhtml", "429723test", 
                   "chrome,width=600,height=600,noopener", window);
 
 ]]>
 </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_bug437844.xul
rename to toolkit/content/tests/chrome/test_bug437844.xhtml

rename from toolkit/content/tests/chrome/test_bug451540.xul
rename to toolkit/content/tests/chrome/test_bug451540.xhtml
--- a/toolkit/content/tests/chrome/test_bug451540.xul
+++ b/toolkit/content/tests/chrome/test_bug451540.xhtml
@@ -25,15 +25,15 @@ https://bugzilla.mozilla.org/show_bug.cg
     </pre>
   </body>
 
   <script class="testbody" type="application/javascript">
     <![CDATA[
 
       /** Test for Bug 451540 **/
       SimpleTest.waitForExplicitFinish();
-      window.openDialog("bug451540_window.xul", "451540test",
+      window.openDialog("bug451540_window.xhtml", "451540test",
                         "chrome,width=600,height=600,noopener", window);
 
     ]]>
   </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_bug457632.xul
rename to toolkit/content/tests/chrome/test_bug457632.xhtml

rename from toolkit/content/tests/chrome/test_bug460942.xul
rename to toolkit/content/tests/chrome/test_bug460942.xhtml

rename from toolkit/content/tests/chrome/test_bug471776.xul
rename to toolkit/content/tests/chrome/test_bug471776.xhtml

rename from toolkit/content/tests/chrome/test_bug509732.xul
rename to toolkit/content/tests/chrome/test_bug509732.xhtml

rename from toolkit/content/tests/chrome/test_bug557987.xul
rename to toolkit/content/tests/chrome/test_bug557987.xhtml

rename from toolkit/content/tests/chrome/test_bug562554.xul
rename to toolkit/content/tests/chrome/test_bug562554.xhtml

rename from toolkit/content/tests/chrome/test_bug624329.xul
rename to toolkit/content/tests/chrome/test_bug624329.xhtml
--- a/toolkit/content/tests/chrome/test_bug624329.xul
+++ b/toolkit/content/tests/chrome/test_bug624329.xhtml
@@ -23,17 +23,17 @@ https://bugzilla.mozilla.org/show_bug.cg
 
 SimpleTest.waitForExplicitFinish();
 
 var win;
 var timeoutID;
 var menu;
 
 function openTestWindow() {
-    win = docShell.rootTreeItem.domWindow.openDialog("bug624329_window.xul", "_blank", "width=300,resizable=yes,chrome", window);
+    win = docShell.rootTreeItem.domWindow.openDialog("bug624329_window.xhtml", "_blank", "width=300,resizable=yes,chrome", window);
     // Close our window if the test times out so that it doesn't interfere
     // with later tests.
     timeoutID = setTimeout(function () {
         ok(false, "Test timed out.");
         // Provide some time for a screenshot
         setTimeout(finish, 1000);
     }, 20000);
 }

rename from toolkit/content/tests/chrome/test_bug792324.xul
rename to toolkit/content/tests/chrome/test_bug792324.xhtml

rename from toolkit/content/tests/chrome/test_button.xul
rename to toolkit/content/tests/chrome/test_button.xhtml

rename from toolkit/content/tests/chrome/test_chromemargin.xul
rename to toolkit/content/tests/chrome/test_chromemargin.xhtml
--- a/toolkit/content/tests/chrome/test_chromemargin.xul
+++ b/toolkit/content/tests/chrome/test_chromemargin.xhtml
@@ -14,17 +14,17 @@
 
 <script>
 
 // Tests parsing of the chrome margin attrib on a window.
 
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.openDialog("window_chromemargin.xul", "_blank", "chrome,width=600,height=600,noopener", window);
+  window.openDialog("window_chromemargin.xhtml", "_blank", "chrome,width=600,height=600,noopener", window);
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_closemenu_attribute.xul
rename to toolkit/content/tests/chrome/test_closemenu_attribute.xhtml

rename from toolkit/content/tests/chrome/test_contextmenu_list.xul
rename to toolkit/content/tests/chrome/test_contextmenu_list.xhtml

rename from toolkit/content/tests/chrome/test_cursorsnap.xul
rename to toolkit/content/tests/chrome/test_cursorsnap.xhtml
--- a/toolkit/content/tests/chrome/test_cursorsnap.xul
+++ b/toolkit/content/tests/chrome/test_cursorsnap.xhtml
@@ -60,47 +60,47 @@ function retryCurrentTest()
 function runCurrentTest()
 {
   var position = "top=" + gTestingCount + ",left=" + gTestingCount + ",";
   gTestingCount++;
   switch (gTestingIndex) {
     case 0:
       gDisable = false;
       gHidden = false;
-      window.openDialog("window_cursorsnap_dialog.xul", "_blank",
+      window.openDialog("window_cursorsnap_dialog.xhtml", "_blank",
                         position + "chrome,width=100,height=100,noopener", window);
       break;
     case 1:
       gDisable = true;
       gHidden = false;
-      window.openDialog("window_cursorsnap_dialog.xul", "_blank",
+      window.openDialog("window_cursorsnap_dialog.xhtml", "_blank",
                         position + "chrome,width=100,height=100,noopener", window);
       break;
     case 2:
       gDisable = false;
       gHidden = true;
-      window.openDialog("window_cursorsnap_dialog.xul", "_blank",
+      window.openDialog("window_cursorsnap_dialog.xhtml", "_blank",
                         position + "chrome,width=100,height=100,noopener", window);
       break;
     case 3:
       gDisable = false;
       gHidden = false;
-      window.openDialog("window_cursorsnap_wizard.xul", "_blank",
+      window.openDialog("window_cursorsnap_wizard.xhtml", "_blank",
                         position + "chrome,width=100,height=100,noopener", window);
       break;
     case 4:
       gDisable = true;
       gHidden = false;
-      window.openDialog("window_cursorsnap_wizard.xul", "_blank",
+      window.openDialog("window_cursorsnap_wizard.xhtml", "_blank",
                         position + "chrome,width=100,height=100,noopener", window);
       break;
     case 5:
       gDisable = false;
       gHidden = true;
-      window.openDialog("window_cursorsnap_wizard.xul", "_blank",
+      window.openDialog("window_cursorsnap_wizard.xhtml", "_blank",
                         position + "chrome,width=100,height=100,noopener", window);
       break;
     default:
       SetPrefs(false);
       SimpleTest.finish();
       return;
   }
 }

rename from toolkit/content/tests/chrome/test_custom_element_base.xul
rename to toolkit/content/tests/chrome/test_custom_element_base.xhtml

rename from toolkit/content/tests/chrome/test_custom_element_delay_connection.xul
rename to toolkit/content/tests/chrome/test_custom_element_delay_connection.xhtml

rename from toolkit/content/tests/chrome/test_deck.xul
rename to toolkit/content/tests/chrome/test_deck.xhtml

rename from toolkit/content/tests/chrome/test_dialogfocus.xul
rename to toolkit/content/tests/chrome/test_dialogfocus.xhtml
--- a/toolkit/content/tests/chrome/test_dialogfocus.xul
+++ b/toolkit/content/tests/chrome/test_dialogfocus.xhtml
@@ -52,17 +52,17 @@ function runTest()
   info("runTest(), step = " + step + ", expected = " + expected[step - 1]);
   if (step > expected.length || (!fullKeyboardAccess && step == 2)) {
     info("finishing");
     SimpleTest.finish();
     return;
   }
 
   var expectedFocus = expected[step - 1];
-  let filename = expectedFocus == "root" ? "dialog_dialogfocus2.xul" : "dialog_dialogfocus.xul";
+  let filename = expectedFocus == "root" ? "dialog_dialogfocus2.xhtml" : "dialog_dialogfocus.xhtml";
   var win = docShell.rootTreeItem.domWindow.openDialog(filename, "_new", "chrome,dialog", step);
 
   function checkDialogFocus(event)
   {
     info(`checkDialogFocus()`);
     let match = false;
     let activeElement = win.document.activeElement;
 

--- a/toolkit/content/tests/chrome/test_edit_contextmenu.html
+++ b/toolkit/content/tests/chrome/test_edit_contextmenu.html
@@ -10,17 +10,17 @@ https://bugzilla.mozilla.org/show_bug.cg
   <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
   <link rel="stylesheet" type="text/css" href="chrome://global/skin"/>
   <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
   <script type="application/javascript">
     const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
     SimpleTest.waitForExplicitFinish();
 
     async function runTest() {
-      let win = window.docShell.rootTreeItem.domWindow.open("file_edit_contextmenu.xul", "context-menu", "chrome,width=600,height=600");
+      let win = window.docShell.rootTreeItem.domWindow.open("file_edit_contextmenu.xhtml", "context-menu", "chrome,width=600,height=600");
       await new Promise(r => win.addEventListener("load", r, { once: true}));
       await SimpleTest.promiseFocus(win);
 
       const elements = [
         win.document.querySelector("textarea"),
         win.document.querySelector("input"),
         win.document.querySelector("search-textbox"),
       ];

rename from toolkit/content/tests/chrome/test_findbar.xul
rename to toolkit/content/tests/chrome/test_findbar.xhtml
--- a/toolkit/content/tests/chrome/test_findbar.xul
+++ b/toolkit/content/tests/chrome/test_findbar.xhtml
@@ -33,15 +33,15 @@ https://bugzilla.mozilla.org/show_bug.cg
 SimpleTest.waitForExplicitFinish();
 
 // Since bug 978861, this pref is set to `false` on OSX. For this test, we'll
 // set it `true` to disable the find clipboard on OSX, which interferes with
 // our tests.
 SpecialPowers.pushPrefEnv({
   set: [["accessibility.typeaheadfind.prefillwithselection", true]]
 }, () => {
-  window.openDialog("findbar_window.xul", "findbartest", "chrome,width=600,height=600,noopener", window);
+  window.openDialog("findbar_window.xhtml", "findbartest", "chrome,width=600,height=600,noopener", window);
 });
 
 ]]>
 </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_findbar_entireword.xul
rename to toolkit/content/tests/chrome/test_findbar_entireword.xhtml
--- a/toolkit/content/tests/chrome/test_findbar_entireword.xul
+++ b/toolkit/content/tests/chrome/test_findbar_entireword.xhtml
@@ -24,15 +24,15 @@ https://bugzilla.mozilla.org/show_bug.cg
     </pre>
   </body>
 
   <script class="testbody" type="application/javascript">
     <![CDATA[
 
       /** Test for Bug 269442 **/
       SimpleTest.waitForExplicitFinish();
-      window.openDialog("findbar_entireword_window.xul", "269442test",
+      window.openDialog("findbar_entireword_window.xhtml", "269442test",
                         "chrome,width=600,height=600,noopener", window);
 
     ]]>
   </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_findbar_events.xul
rename to toolkit/content/tests/chrome/test_findbar_events.xhtml
--- a/toolkit/content/tests/chrome/test_findbar_events.xul
+++ b/toolkit/content/tests/chrome/test_findbar_events.xhtml
@@ -24,15 +24,15 @@ https://bugzilla.mozilla.org/show_bug.cg
     </pre>
   </body>
 
   <script class="testbody" type="application/javascript">
     <![CDATA[
 
       /** Test for Bug 793275 **/
       SimpleTest.waitForExplicitFinish();
-      window.openDialog("findbar_events_window.xul", "793275test",
+      window.openDialog("findbar_events_window.xhtml", "793275test",
                         "chrome,width=600,height=600,noopener", window);
 
     ]]>
   </script>
 
 </window>

rename from toolkit/content/tests/chrome/test_frames.xul
rename to toolkit/content/tests/chrome/test_frames.xhtml

rename from toolkit/content/tests/chrome/test_hiddenitems.xul
rename to toolkit/content/tests/chrome/test_hiddenitems.xhtml

rename from toolkit/content/tests/chrome/test_hiddenpaging.xul
rename to toolkit/content/tests/chrome/test_hiddenpaging.xhtml

rename from toolkit/content/tests/chrome/test_keys.xul
rename to toolkit/content/tests/chrome/test_keys.xhtml
--- a/toolkit/content/tests/chrome/test_keys.xul
+++ b/toolkit/content/tests/chrome/test_keys.xhtml
@@ -7,17 +7,17 @@
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
 
 <script>
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.openDialog("window_keys.xul", "_blank", "chrome,width=200,height=200,noopener", window);
+  window.openDialog("window_keys.xhtml", "_blank", "chrome,width=200,height=200,noopener", window);
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_labelcontrol.xul
rename to toolkit/content/tests/chrome/test_labelcontrol.xhtml

--- a/toolkit/content/tests/chrome/test_largemenu.html
+++ b/toolkit/content/tests/chrome/test_largemenu.html
@@ -3,17 +3,17 @@
 <head>
   <meta charset="utf-8">
   <title>Large Menu Tests</title>
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
   <script>
     SimpleTest.waitForExplicitFinish();
     function runTest() {
-      window.openDialog("window_largemenu.xul", "_blank", "chrome,width=200,height=200,noopener", window);
+      window.openDialog("window_largemenu.xhtml", "_blank", "chrome,width=200,height=200,noopener", window);
     }
   </script>
 </head>
 <body onload="setTimeout(runTest, 0);">
 <p id="display"></p>
 <div id="content" style="display: none"></div>
 <pre id="test">
 </pre>

rename from toolkit/content/tests/chrome/test_maximized_persist.xul
rename to toolkit/content/tests/chrome/test_maximized_persist.xhtml
--- a/toolkit/content/tests/chrome/test_maximized_persist.xul
+++ b/toolkit/content/tests/chrome/test_maximized_persist.xhtml
@@ -22,17 +22,17 @@
         }
       }
       window.addEventListener("message", listener);
     });
   }
 
   function openWindow(features = "") {
     return docShell.rootTreeItem.domWindow.openDialog(
-        "window_maximized_persist.xul",
+        "window_maximized_persist.xhtml",
         "_blank", "chrome,dialog=no,all," + features, window);
   }
 
   function checkWindow(msg, win, sizemode, width, height) {
     is(win.windowState, sizemode, "sizemode should match " + msg);
     if (sizemode == win.STATE_NORMAL) {
       is(win.innerWidth, width, "width should match " + msg);
       is(win.innerHeight, height, "height should match " + msg);

rename from toolkit/content/tests/chrome/test_menu.xul
rename to toolkit/content/tests/chrome/test_menu.xhtml

rename from toolkit/content/tests/chrome/test_menu_hide.xul
rename to toolkit/content/tests/chrome/test_menu_hide.xhtml

rename from toolkit/content/tests/chrome/test_menu_withcapture.xul
rename to toolkit/content/tests/chrome/test_menu_withcapture.xhtml

rename from toolkit/content/tests/chrome/test_menuchecks.xul
rename to toolkit/content/tests/chrome/test_menuchecks.xhtml

rename from toolkit/content/tests/chrome/test_menuitem_blink.xul
rename to toolkit/content/tests/chrome/test_menuitem_blink.xhtml

rename from toolkit/content/tests/chrome/test_menuitem_commands.xul
rename to toolkit/content/tests/chrome/test_menuitem_commands.xhtml
--- a/toolkit/content/tests/chrome/test_menuitem_commands.xul
+++ b/toolkit/content/tests/chrome/test_menuitem_commands.xhtml
@@ -23,17 +23,17 @@ function checkAttributes(elem, label, ac
 }
 
 function runOrOpen()
 {
   if (window.arguments) {
     SimpleTest.waitForFocus(runTest);
   }
   else {
-    window.openDialog("test_menuitem_commands.xul", "", "chrome,noopener", window);
+    window.openDialog("test_menuitem_commands.xhtml", "", "chrome,noopener", window);
   }
 }
 
 function runTest()
 {
   runTestSet("");
   runTestSet("bar");
   window.close();

rename from toolkit/content/tests/chrome/test_menulist.xul
rename to toolkit/content/tests/chrome/test_menulist.xhtml

rename from toolkit/content/tests/chrome/test_menulist_keynav.xul
rename to toolkit/content/tests/chrome/test_menulist_keynav.xhtml

rename from toolkit/content/tests/chrome/test_menulist_null_value.xul
rename to toolkit/content/tests/chrome/test_menulist_null_value.xhtml

rename from toolkit/content/tests/chrome/test_menulist_paging.xul
rename to toolkit/content/tests/chrome/test_menulist_paging.xhtml

rename from toolkit/content/tests/chrome/test_menulist_position.xul
rename to toolkit/content/tests/chrome/test_menulist_position.xhtml

rename from toolkit/content/tests/chrome/test_mousescroll.xul
rename to toolkit/content/tests/chrome/test_mousescroll.xhtml

rename from toolkit/content/tests/chrome/test_mozinputbox_dictionary.xul
rename to toolkit/content/tests/chrome/test_mozinputbox_dictionary.xhtml

rename from toolkit/content/tests/chrome/test_notificationbox.xul
rename to toolkit/content/tests/chrome/test_notificationbox.xhtml

rename from toolkit/content/tests/chrome/test_panel.xul
rename to toolkit/content/tests/chrome/test_panel.xhtml
--- a/toolkit/content/tests/chrome/test_panel.xul
+++ b/toolkit/content/tests/chrome/test_panel.xhtml
@@ -8,17 +8,17 @@
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
   <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
 
 <script>
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.openDialog("window_panel.xul", "_blank", "chrome,left=200,top=200,width=200,height=200,noopener", window);
+  window.openDialog("window_panel.xhtml", "_blank", "chrome,left=200,top=200,width=200,height=200,noopener", window);
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_panel_anchoradjust.xul
rename to toolkit/content/tests/chrome/test_panel_anchoradjust.xhtml
--- a/toolkit/content/tests/chrome/test_panel_anchoradjust.xul
+++ b/toolkit/content/tests/chrome/test_panel_anchoradjust.xhtml
@@ -8,17 +8,17 @@
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
   <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
 
 <script>
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.openDialog("window_panel_anchoradjust.xul", "_blank", "chrome,left=200,top=200,width=200,height=200,noopener", window);
+  window.openDialog("window_panel_anchoradjust.xhtml", "_blank", "chrome,left=200,top=200,width=200,height=200,noopener", window);
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_panel_focus.xul
rename to toolkit/content/tests/chrome/test_panel_focus.xhtml
--- a/toolkit/content/tests/chrome/test_panel_focus.xul
+++ b/toolkit/content/tests/chrome/test_panel_focus.xhtml
@@ -15,17 +15,17 @@
  
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
   // move the mouse so any tooltips that might be open go away, otherwise this
   // test can fail on Mac
   synthesizeMouse(document.documentElement, 1, 1, { type: "mousemove" });
 
-  window.openDialog("window_panel_focus.xul", "_blank", "chrome,width=600,height=600,noopener", window);
+  window.openDialog("window_panel_focus.xhtml", "_blank", "chrome,width=600,height=600,noopener", window);
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_panelfrommenu.xul
rename to toolkit/content/tests/chrome/test_panelfrommenu.xhtml

rename from toolkit/content/tests/chrome/test_popup_anchor.xul
rename to toolkit/content/tests/chrome/test_popup_anchor.xhtml
--- a/toolkit/content/tests/chrome/test_popup_anchor.xul
+++ b/toolkit/content/tests/chrome/test_popup_anchor.xhtml
@@ -8,17 +8,17 @@
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
 
 <script>
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.openDialog("window_popup_anchor.xul", "_blank", "chrome,width=600,height=600,noopener", window);
+  window.openDialog("window_popup_anchor.xhtml", "_blank", "chrome,width=600,height=600,noopener", window);
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_popup_anchoratrect.xul
rename to toolkit/content/tests/chrome/test_popup_anchoratrect.xhtml
--- a/toolkit/content/tests/chrome/test_popup_anchoratrect.xul
+++ b/toolkit/content/tests/chrome/test_popup_anchoratrect.xhtml
@@ -7,17 +7,17 @@
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>      
 
 <script>
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.openDialog("window_popup_anchoratrect.xul", "_blank", "chrome,width=200,height=200,noopener", window);
+  window.openDialog("window_popup_anchoratrect.xhtml", "_blank", "chrome,width=200,height=200,noopener", window);
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_popup_attribute.xul
rename to toolkit/content/tests/chrome/test_popup_attribute.xhtml
--- a/toolkit/content/tests/chrome/test_popup_attribute.xul
+++ b/toolkit/content/tests/chrome/test_popup_attribute.xhtml
@@ -7,17 +7,17 @@
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>      
 
 <script>
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.open("window_popup_attribute.xul", "_blank", "width=600,height=700");
+  window.open("window_popup_attribute.xhtml", "_blank", "width=600,height=700");
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_popup_button.xul
rename to toolkit/content/tests/chrome/test_popup_button.xhtml
--- a/toolkit/content/tests/chrome/test_popup_button.xul
+++ b/toolkit/content/tests/chrome/test_popup_button.xhtml
@@ -7,17 +7,17 @@
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>      
 
 <script>
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.open("window_popup_button.xul", "_blank", "width=700,height=700");
+  window.open("window_popup_button.xhtml", "_blank", "width=700,height=700");
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_popup_coords.xul
rename to toolkit/content/tests/chrome/test_popup_coords.xhtml

rename from toolkit/content/tests/chrome/test_popup_keys.xul
rename to toolkit/content/tests/chrome/test_popup_keys.xhtml

rename from toolkit/content/tests/chrome/test_popup_moveToAnchor.xul
rename to toolkit/content/tests/chrome/test_popup_moveToAnchor.xhtml

rename from toolkit/content/tests/chrome/test_popup_preventdefault.xul
rename to toolkit/content/tests/chrome/test_popup_preventdefault.xhtml

rename from toolkit/content/tests/chrome/test_popup_preventdefault_chrome.xul
rename to toolkit/content/tests/chrome/test_popup_preventdefault_chrome.xhtml
--- a/toolkit/content/tests/chrome/test_popup_preventdefault_chrome.xul
+++ b/toolkit/content/tests/chrome/test_popup_preventdefault_chrome.xhtml
@@ -7,17 +7,17 @@
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
 
 <script>
 SimpleTest.waitForExplicitFinish();
 function runTest()
 {
-  window.openDialog("window_popup_preventdefault_chrome.xul", "_blank", "chrome,width=600,height=600,noopener", window);
+  window.openDialog("window_popup_preventdefault_chrome.xhtml", "_blank", "chrome,width=600,height=600,noopener", window);
 }
 </script>
 
 <body xmlns="http://www.w3.org/1999/xhtml">
 <p id="display">
 </p>
 <div id="content" style="display: none">
 </div>

rename from toolkit/content/tests/chrome/test_popup_recreate.xul
rename to toolkit/content/tests/chrome/test_popup_recreate.xhtml

rename from toolkit/content/tests/chrome/test_popup_scaled.xul
rename to toolkit/content/tests/chrome/test_popup_scaled.xhtml

rename from toolkit/content/tests/chrome/test_popup_tree.xul
rename to toolkit/content/tests/chrome/test_popup_tree.xhtml

rename from toolkit/content/tests/chrome/test_popuphidden.xul
rename to toolkit/content/tests/chrome/test_popuphidden.xhtml

rename from toolkit/content/tests/chrome/test_popupincontent.xul
rename to toolkit/content/tests/chrome/test_popupincontent.xhtml

rename from toolkit/content/tests/chrome/test_popupremoving.xul
rename to toolkit/content/tests/chrome/test_popupremoving.xhtml

rename from toolkit/content/tests/chrome/test_popupremoving_frame.xul
rename to toolkit/content/tests/chrome/test_popupremoving_frame.xhtml
--- a/toolkit/content/tests/chrome/test_popupremoving_frame.xul
+++ b/toolkit/content/tests/chrome/test_popupremoving_frame.xhtml
@@ -7,17 +7,17 @@
 
 <!--
   This test checks that popup elements are removed when the document is changed.
   -->
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>      
   <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>      
 
-<iframe id="frame" width="300" height="150" src="frame_popupremoving_frame.xul"/>
+<iframe id="frame" width="300" height="150" src="frame_popupremoving_frame.xhtml"/>
 
 <script class="testbody" type="application/javascript">
 <![CDATA[
 
 SimpleTest.waitForExplicitFinish();
 
 var gMenus = [];
 

rename from toolkit/content/tests/chrome/test_position.xul
rename to toolkit/content/tests/chrome/test_position.xhtml

rename from toolkit/content/tests/chrome/test_preferences.xul
rename to toolkit/content/tests/chrome/test_preferences.xhtml
--- a/toolkit/content/tests/chrome/test_preferences.xul
+++ b/toolkit/content/tests/chrome/test_preferences.xhtml
@@ -430,78 +430,78 @@
       kPref.setBoolPref("browser.preferences.instantApply", aInstantApply);
       WritePrefsToSystem(kPrefValueSet1);
     }
 
     function RunTestInstant()
     {
       // test with instantApply
       InitTestPrefs(true);
-      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences.xul", "", "modal", RunInstantPrefTest, false);
+      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences.xhtml", "", "modal", RunInstantPrefTest, false);
 
       // - test deferred reset in child window
       InitTestPrefs(true);
-      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences2.xul", "", "modal", RunResetPrefTest, false);
+      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences2.xhtml", "", "modal", RunResetPrefTest, false);
       expected = kPrefValueSet1;
       found    = ReadPrefsFromSystem();
       ok(found.int          === expected.int,          "instant reset deferred int"    );
       ok(found.bool         === expected.bool,         "instant reset deferred bool"   );
       ok(found.string       === expected.string,       "instant reset deferred string" );
       ok(found.unichar      === expected.unichar,      "instant reset deferred unichar");
       ok(found.wstring_data === expected.wstring_data, "instant reset deferred wstring");
       todo(found.file_data  === expected.file_data,    "instant reset deferred file"   );
     }
 
     function RunTestNonInstant()
     {
       // test without instantApply
       // - general tests, similar to instant apply
       InitTestPrefs(false);
-      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences.xul", "", "modal", RunNonInstantPrefTestGeneral, false);
+      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences.xhtml", "", "modal", RunNonInstantPrefTestGeneral, false);
 
       // - test Cancel
       InitTestPrefs(false);
-      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences.xul", "", "modal", RunNonInstantPrefTestClose, false);
+      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences.xhtml", "", "modal", RunNonInstantPrefTestClose, false);
       var expected = kPrefValueSet1;
       var found    = ReadPrefsFromSystem();
       ok(found.int          === expected.int,          "non-instant cancel system int"    );
       ok(found.bool         === expected.bool,         "non-instant cancel system bool"   );
       ok(found.string       === expected.string,       "non-instant cancel system string" );
       ok(found.unichar      === expected.unichar,      "non-instant cancel system unichar");
       ok(found.wstring_data === expected.wstring_data, "non-instant cancel system wstring");
       todo(found.file_data  === expected.file_data,    "non-instant cancel system file"   );
       
       // - test Accept
       InitTestPrefs(false);
-      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences.xul", "", "modal", RunNonInstantPrefTestClose, true);
+      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences.xhtml", "", "modal", RunNonInstantPrefTestClose, true);
       expected = kPrefValueSet2;
       found    = ReadPrefsFromSystem();
       ok(found.int          === expected.int,          "non-instant accept system int"    );
       ok(found.bool         === expected.bool,         "non-instant accept system bool"   );
       ok(found.string       === expected.string,       "non-instant accept system string" );
       ok(found.unichar      === expected.unichar,      "non-instant accept system unichar");
       ok(found.wstring_data === expected.wstring_data, "non-instant accept system wstring");
       todo(found.file_data  === expected.file_data,    "non-instant accept system file"   );
 
       // - test deferred reset in child window
       InitTestPrefs(false);
-      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences2.xul", "", "modal", RunResetPrefTest, true);
+      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences2.xhtml", "", "modal", RunResetPrefTest, true);
       expected = CreateEmptyPrefValueSet();
       found    = ReadPrefsFromSystem();
       ok(found.int          === expected.int,          "non-instant reset deferred int"    );
       ok(found.bool         === expected.bool,         "non-instant reset deferred bool"   );
       ok(found.string       === expected.string,       "non-instant reset deferred string" );
       ok(found.unichar      === expected.unichar,      "non-instant reset deferred unichar");
       ok(found.wstring_data === expected.wstring_data, "non-instant reset deferred wstring");
       ok(found.file_data    === expected.file_data,    "non-instant reset deferred file"   );
     }
 
     function RunTestCommandRedirect()
     {
-      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences_commandretarget.xul", "", "modal", RunCheckCommandRedirect, true);
+      window.docShell.rootTreeItem.domWindow.openDialog("window_preferences_commandretarget.xhtml", "", "modal", RunCheckCommandRedirect, true);
     }
 
     function RunTest()
     {
       RunTestInstant();
       RunTestNonInstant();
       RunTestCommandRedirect();
       SimpleTest.finish();