dom/base/Element.cpp
author Emilio Cobos Álvarez <emilio@crisal.io>
Thu, 08 Nov 2018 20:55:22 +0000
changeset 445207 853e4a06fb03aee6c1a732a8d594a3bfd14d97a2
parent 444102 17f76aad81aa5027af1c769d647dcc1916403c9e
child 446408 06b12fd41ff14bbcba2d2bf268ad5da44496a02a
permissions -rw-r--r--
Bug 1505875 - Clear out the ShadowRoot host pointer when unattaching it. r=smaug As expected, this is specific to the UA widget stuff. What's going on here is that given we don't clear out the host when unattaching the shadow tree, mutating that shadow tree still notifies all the way up to the document, and that gets all the other code confused, thinking that the node is connected. Indeed, the first assertion that fails when loading that test-case in a debug build is: https://searchfox.org/mozilla-central/rev/17f55aee76b7c4610a974cffd3453454e0c8de7b/dom/base/nsNodeUtils.cpp#93 This seems the best fix to avoid confusion. Also clear the mutation observer, to completely forget about the host. Chrome code dealing with UA widgets needs to be careful, but I think this is safe. All the code that assumes that GetHost() doesn't return null is in code dealing with connected shadow trees only (style system / layout), or in mutation observer notifications from the host. Differential Revision: https://phabricator.services.mozilla.com/D11369

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

/*
 * Base class for all element classes; this provides an implementation
 * of DOM Core's Element, implements nsIContent, provides
 * utility methods for subclasses, and so forth.
 */

#include "mozilla/dom/ElementInlines.h"

#include "AnimationCommon.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/StaticPrefs.h"
#include "mozilla/dom/Animation.h"
#include "mozilla/dom/Attr.h"
#include "mozilla/dom/Flex.h"
#include "mozilla/dom/Grid.h"
#include "mozilla/gfx/Matrix.h"
#include "nsAtom.h"
#include "nsCSSFrameConstructor.h"
#include "nsDOMAttributeMap.h"
#include "nsIContentInlines.h"
#include "mozilla/dom/NodeInfo.h"
#include "nsIDocumentInlines.h"
#include "mozilla/dom/DocumentTimeline.h"
#include "nsIContentIterator.h"
#include "nsFlexContainerFrame.h"
#include "nsFocusManager.h"
#include "nsILinkHandler.h"
#include "nsIScriptGlobalObject.h"
#include "nsIURL.h"
#include "nsContainerFrame.h"
#include "nsIAnonymousContentCreator.h"
#include "nsIPresShell.h"
#include "nsPresContext.h"
#include "nsStyleConsts.h"
#include "nsString.h"
#include "nsUnicharUtils.h"
#include "nsDOMCID.h"
#include "nsIServiceManager.h"
#include "nsDOMCSSAttrDeclaration.h"
#include "nsNameSpaceManager.h"
#include "nsContentList.h"
#include "nsVariant.h"
#include "nsDOMTokenList.h"
#include "nsXBLPrototypeBinding.h"
#include "nsError.h"
#include "nsDOMString.h"
#include "nsIScriptSecurityManager.h"
#include "mozilla/dom/AnimatableBinding.h"
#include "mozilla/dom/FeaturePolicyUtils.h"
#include "mozilla/dom/HTMLDivElement.h"
#include "mozilla/dom/HTMLSpanElement.h"
#include "mozilla/dom/KeyframeAnimationOptionsBinding.h"
#include "mozilla/dom/MutationEventBinding.h"
#include "mozilla/AnimationComparator.h"
#include "mozilla/AsyncEventDispatcher.h"
#include "mozilla/ContentEvents.h"
#include "mozilla/DeclarationBlock.h"
#include "mozilla/EffectSet.h"
#include "mozilla/EventDispatcher.h"
#include "mozilla/EventListenerManager.h"
#include "mozilla/EventStateManager.h"
#include "mozilla/EventStates.h"
#include "mozilla/FullscreenChange.h"
#include "mozilla/InternalMutationEvent.h"
#include "mozilla/MouseEvents.h"
#include "mozilla/RestyleManager.h"
#include "mozilla/SizeOfState.h"
#include "mozilla/TextEditor.h"
#include "mozilla/TextEvents.h"
#include "nsNodeUtils.h"
#include "mozilla/dom/DirectionalityUtils.h"
#include "nsDocument.h"
#include "nsAttrValueOrString.h"
#include "nsAttrValueInlines.h"
#include "nsCSSPseudoElements.h"
#include "nsWindowSizes.h"
#ifdef MOZ_XUL
#include "nsXULElement.h"
#endif /* MOZ_XUL */
#include "nsSVGElement.h"
#include "nsFrameSelection.h"
#ifdef DEBUG
#include "nsRange.h"
#endif

#include "nsBindingManager.h"
#include "nsXBLBinding.h"
#include "nsPIDOMWindow.h"
#include "nsPIBoxObject.h"
#include "mozilla/dom/DOMRect.h"
#include "nsSVGUtils.h"
#include "nsLayoutUtils.h"
#include "nsGkAtoms.h"
#include "nsContentUtils.h"
#include "ChildIterator.h"

#include "nsIDOMEventListener.h"
#include "nsIWebNavigation.h"
#include "nsIBaseWindow.h"
#include "nsIWidget.h"

#include "nsNodeInfoManager.h"
#include "nsICategoryManager.h"
#include "nsGenericHTMLElement.h"
#include "nsContentCreatorFunctions.h"
#include "nsIControllers.h"
#include "nsView.h"
#include "nsViewManager.h"
#include "nsIScrollableFrame.h"
#include "nsTextNode.h"

#include "nsCycleCollectionParticipant.h"
#include "nsCCUncollectableMarker.h"

#include "mozAutoDocUpdate.h"

#include "nsDOMMutationObserver.h"
#include "nsWrapperCacheInlines.h"
#include "xpcpublic.h"
#include "nsIScriptError.h"
#include "mozilla/Telemetry.h"

#include "mozilla/CORSMode.h"
#include "mozilla/dom/ShadowRoot.h"
#include "mozilla/dom/NodeListBinding.h"

#include "nsStyledElement.h"
#include "nsXBLService.h"
#include "nsITextControlElement.h"
#include "nsITextControlFrame.h"
#include "nsISupportsImpl.h"
#include "mozilla/dom/CSSPseudoElement.h"
#include "mozilla/dom/DocumentFragment.h"
#include "mozilla/dom/ElementBinding.h"
#include "mozilla/dom/KeyframeEffectBinding.h"
#include "mozilla/dom/KeyframeEffect.h"
#include "mozilla/dom/MouseEventBinding.h"
#include "mozilla/dom/WindowBinding.h"
#include "mozilla/dom/VRDisplay.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/Preferences.h"
#include "nsComputedDOMStyle.h"
#include "nsDOMStringMap.h"
#include "DOMIntersectionObserver.h"

#include "nsISpeculativeConnect.h"
#include "nsIIOService.h"

#include "DOMMatrix.h"

using namespace mozilla;
using namespace mozilla::dom;

using mozilla::gfx::Matrix4x4;

//
// Verify sizes of elements on 64-bit platforms. This should catch most memory
// regressions, and is easy to verify locally since most developers are on
// 64-bit machines. We use a template rather than a direct static assert so
// that the error message actually displays the sizes.
//

// We need different numbers on certain build types to deal with the owning
// thread pointer that comes with the non-threadsafe refcount on
// FragmentOrElement.
#ifdef MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
#define EXTRA_DOM_ELEMENT_BYTES 8
#else
#define EXTRA_DOM_ELEMENT_BYTES 0
#endif

#define ASSERT_ELEMENT_SIZE(type, opt_size) \
template<int a, int b> struct Check##type##Size \
{ \
  static_assert(sizeof(void*) != 8 || a == b, "DOM size changed"); \
}; \
Check##type##Size<sizeof(type), opt_size + EXTRA_DOM_ELEMENT_BYTES> g##type##CES;

// Note that mozjemalloc uses a 16 byte quantum, so 128 is a bin/bucket size.
ASSERT_ELEMENT_SIZE(Element, 128);
ASSERT_ELEMENT_SIZE(HTMLDivElement, 128);
ASSERT_ELEMENT_SIZE(HTMLSpanElement, 128);

#undef ASSERT_ELEMENT_SIZE
#undef EXTRA_DOM_ELEMENT_BYTES

nsAtom*
nsIContent::DoGetID() const
{
  MOZ_ASSERT(HasID(), "Unexpected call");
  MOZ_ASSERT(IsElement(), "Only elements can have IDs");

  return AsElement()->GetParsedAttr(nsGkAtoms::id)->GetAtomValue();
}

const nsAttrValue*
Element::GetSVGAnimatedClass() const
{
  MOZ_ASSERT(MayHaveClass() && IsSVGElement(), "Unexpected call");
  return static_cast<const nsSVGElement*>(this)->GetAnimatedClassName();
}

NS_IMETHODIMP
Element::QueryInterface(REFNSIID aIID, void** aInstancePtr)
{
  if (aIID.Equals(NS_GET_IID(Element))) {
    NS_ADDREF_THIS();
    *aInstancePtr = this;
    return NS_OK;
  }

  NS_ASSERTION(aInstancePtr,
               "QueryInterface requires a non-NULL destination!");
  nsresult rv = FragmentOrElement::QueryInterface(aIID, aInstancePtr);
  if (NS_SUCCEEDED(rv)) {
    return NS_OK;
  }

  // Give the binding manager a chance to get an interface for this element.
  return OwnerDoc()->BindingManager()->GetBindingImplementation(this, aIID,
                                                                aInstancePtr);
}

EventStates
Element::IntrinsicState() const
{
  return IsEditable() ? NS_EVENT_STATE_MOZ_READWRITE :
                        NS_EVENT_STATE_MOZ_READONLY;
}

void
Element::NotifyStateChange(EventStates aStates)
{
  nsIDocument* doc = GetComposedDoc();
  if (doc) {
    nsAutoScriptBlocker scriptBlocker;
    doc->ContentStateChanged(this, aStates);
  }
}

void
Element::UpdateLinkState(EventStates aState)
{
  MOZ_ASSERT(!aState.HasAtLeastOneOfStates(~(NS_EVENT_STATE_VISITED |
                                             NS_EVENT_STATE_UNVISITED)),
             "Unexpected link state bits");
  mState =
    (mState & ~(NS_EVENT_STATE_VISITED | NS_EVENT_STATE_UNVISITED)) |
    aState;
}

void
Element::UpdateState(bool aNotify)
{
  EventStates oldState = mState;
  mState = IntrinsicState() | (oldState & EXTERNALLY_MANAGED_STATES);
  if (aNotify) {
    EventStates changedStates = oldState ^ mState;
    if (!changedStates.IsEmpty()) {
      nsIDocument* doc = GetComposedDoc();
      if (doc) {
        nsAutoScriptBlocker scriptBlocker;
        doc->ContentStateChanged(this, changedStates);
      }
    }
  }
}

void
nsIContent::UpdateEditableState(bool aNotify)
{
  // Guaranteed to be non-element content
  NS_ASSERTION(!IsElement(), "What happened here?");
  nsIContent *parent = GetParent();

  // Skip over unknown native anonymous content to avoid setting a flag we
  // can't clear later
  bool isUnknownNativeAnon = false;
  if (IsInNativeAnonymousSubtree()) {
    isUnknownNativeAnon = true;
    nsCOMPtr<nsIContent> root = this;
    while (root && !root->IsRootOfNativeAnonymousSubtree()) {
      root = root->GetParent();
    }
    // root should always be true here, but isn't -- bug 999416
    if (root) {
      nsIFrame* rootFrame = root->GetPrimaryFrame();
      if (rootFrame) {
        nsContainerFrame* parentFrame = rootFrame->GetParent();
        nsITextControlFrame* textCtrl = do_QueryFrame(parentFrame);
        isUnknownNativeAnon = !textCtrl;
      }
    }
  }

  SetEditableFlag(parent && parent->HasFlag(NODE_IS_EDITABLE) &&
                  !isUnknownNativeAnon);
}

void
Element::UpdateEditableState(bool aNotify)
{
  nsIContent *parent = GetParent();

  SetEditableFlag(parent && parent->HasFlag(NODE_IS_EDITABLE));
  if (aNotify) {
    UpdateState(aNotify);
  } else {
    // Avoid calling UpdateState in this very common case, because
    // this gets called for pretty much every single element on
    // insertion into the document and UpdateState can be slow for
    // some kinds of elements even when not notifying.
    if (IsEditable()) {
      RemoveStatesSilently(NS_EVENT_STATE_MOZ_READONLY);
      AddStatesSilently(NS_EVENT_STATE_MOZ_READWRITE);
    } else {
      RemoveStatesSilently(NS_EVENT_STATE_MOZ_READWRITE);
      AddStatesSilently(NS_EVENT_STATE_MOZ_READONLY);
    }
  }
}

int32_t
Element::TabIndex()
{
  const nsAttrValue* attrVal = mAttrs.GetAttr(nsGkAtoms::tabindex);
  if (attrVal && attrVal->Type() == nsAttrValue::eInteger) {
    return attrVal->GetIntegerValue();
  }

  return TabIndexDefault();
}

void
Element::Focus(mozilla::ErrorResult& aError)
{
  nsFocusManager* fm = nsFocusManager::GetFocusManager();
  // Also other browsers seem to have the hack to not re-focus (and flush) when
  // the element is already focused.
  if (fm) {
    if (fm->CanSkipFocus(this)) {
      fm->NeedsFlushBeforeEventHandling(this);
    } else {
      aError = fm->SetFocus(this, 0);
    }
  }
}

void
Element::SetTabIndex(int32_t aTabIndex, mozilla::ErrorResult& aError)
{
  nsAutoString value;
  value.AppendInt(aTabIndex);

  SetAttr(nsGkAtoms::tabindex, value, aError);
}

void
Element::SetXBLBinding(nsXBLBinding* aBinding,
                       nsBindingManager* aOldBindingManager)
{
  nsBindingManager* bindingManager;
  if (aOldBindingManager) {
    MOZ_ASSERT(!aBinding, "aOldBindingManager should only be provided "
                          "when removing a binding.");
    bindingManager = aOldBindingManager;
  } else {
    bindingManager = OwnerDoc()->BindingManager();
  }

  // After this point, aBinding will be the most-derived binding for aContent.
  // If we already have a binding for aContent, make sure to
  // remove it from the attached stack.  Otherwise we might end up firing its
  // constructor twice (if aBinding inherits from it) or firing its constructor
  // after aContent has been deleted (if aBinding is null and the content node
  // dies before we process mAttachedStack).
  RefPtr<nsXBLBinding> oldBinding = GetXBLBinding();
  if (oldBinding) {
    bindingManager->RemoveFromAttachedQueue(oldBinding);
  }

  if (aBinding) {
    SetFlags(NODE_MAY_BE_IN_BINDING_MNGR);
    nsExtendedDOMSlots* slots = ExtendedDOMSlots();
    slots->mXBLBinding = aBinding;
    bindingManager->AddBoundContent(this);
  } else {
    nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
    if (slots) {
      slots->mXBLBinding = nullptr;
    }
    bindingManager->RemoveBoundContent(this);
    if (oldBinding) {
      oldBinding->SetBoundElement(nullptr);
    }
  }
}

void
Element::SetShadowRoot(ShadowRoot* aShadowRoot)
{
  nsExtendedDOMSlots* slots = ExtendedDOMSlots();
  slots->mShadowRoot = aShadowRoot;
}

void
Element::Blur(mozilla::ErrorResult& aError)
{
  if (!ShouldBlur(this)) {
    return;
  }

  nsIDocument* doc = GetComposedDoc();
  if (!doc) {
    return;
  }

  nsPIDOMWindowOuter* win = doc->GetWindow();
  nsIFocusManager* fm = nsFocusManager::GetFocusManager();
  if (win && fm) {
    aError = fm->ClearFocus(win);
  }
}

EventStates
Element::StyleStateFromLocks() const
{
  StyleStateLocks locksAndValues = LockedStyleStates();
  EventStates locks = locksAndValues.mLocks;
  EventStates values = locksAndValues.mValues;
  EventStates state = (mState & ~locks) | (locks & values);

  if (state.HasState(NS_EVENT_STATE_VISITED)) {
    return state & ~NS_EVENT_STATE_UNVISITED;
  }
  if (state.HasState(NS_EVENT_STATE_UNVISITED)) {
    return state & ~NS_EVENT_STATE_VISITED;
  }

  return state;
}

Element::StyleStateLocks
Element::LockedStyleStates() const
{
  StyleStateLocks* locks =
    static_cast<StyleStateLocks*>(GetProperty(nsGkAtoms::lockedStyleStates));
  if (locks) {
    return *locks;
  }
  return StyleStateLocks();
}

void
Element::NotifyStyleStateChange(EventStates aStates)
{
  nsIDocument* doc = GetComposedDoc();
  if (doc) {
    nsIPresShell *presShell = doc->GetShell();
    if (presShell) {
      nsAutoScriptBlocker scriptBlocker;
      presShell->ContentStateChanged(doc, this, aStates);
    }
  }
}

void
Element::LockStyleStates(EventStates aStates, bool aEnabled)
{
  StyleStateLocks* locks = new StyleStateLocks(LockedStyleStates());

  locks->mLocks |= aStates;
  if (aEnabled) {
    locks->mValues |= aStates;
  } else {
    locks->mValues &= ~aStates;
  }

  if (aStates.HasState(NS_EVENT_STATE_VISITED)) {
    locks->mLocks &= ~NS_EVENT_STATE_UNVISITED;
  }
  if (aStates.HasState(NS_EVENT_STATE_UNVISITED)) {
    locks->mLocks &= ~NS_EVENT_STATE_VISITED;
  }

  SetProperty(nsGkAtoms::lockedStyleStates, locks,
              nsINode::DeleteProperty<StyleStateLocks>);
  SetHasLockedStyleStates();

  NotifyStyleStateChange(aStates);
}

void
Element::UnlockStyleStates(EventStates aStates)
{
  StyleStateLocks* locks = new StyleStateLocks(LockedStyleStates());

  locks->mLocks &= ~aStates;

  if (locks->mLocks.IsEmpty()) {
    DeleteProperty(nsGkAtoms::lockedStyleStates);
    ClearHasLockedStyleStates();
    delete locks;
  }
  else {
    SetProperty(nsGkAtoms::lockedStyleStates, locks,
                nsINode::DeleteProperty<StyleStateLocks>);
  }

  NotifyStyleStateChange(aStates);
}

void
Element::ClearStyleStateLocks()
{
  StyleStateLocks locks = LockedStyleStates();

  DeleteProperty(nsGkAtoms::lockedStyleStates);
  ClearHasLockedStyleStates();

  NotifyStyleStateChange(locks.mLocks);
}

static bool
IsLikelyCustomElement(const nsXULElement& aElement)
{
  const CustomElementData* data = aElement.GetCustomElementData();
  if (!data) {
    return false;
  }

  const CustomElementRegistry* registry =
    nsContentUtils::GetCustomElementRegistry(aElement.OwnerDoc());
  if (!registry) {
    return false;
  }

  return registry->IsLikelyToBeCustomElement(data->GetCustomElementType());
}

static bool
MayNeedToLoadXBLBinding(const nsIDocument& aDocument, const Element& aElement)
{
  // If we have a frame, the frame has already loaded the binding.
  // Otherwise, don't do anything else here unless we're dealing with
  // XUL or an HTML element that may have a plugin-related overlay
  // (i.e. object or embed).
  if (!aDocument.GetShell() || aElement.GetPrimaryFrame()) {
    return false;
  }

  if (auto* xulElem = nsXULElement::FromNode(aElement)) {
    return !IsLikelyCustomElement(*xulElem);
  }

  return aElement.IsAnyOfHTMLElements(nsGkAtoms::object, nsGkAtoms::embed);
}

bool
Element::GetBindingURL(nsIDocument *aDocument, css::URLValue **aResult)
{
  if (!MayNeedToLoadXBLBinding(*aDocument, *this)) {
    *aResult = nullptr;
    return true;
  }

  // Get the computed -moz-binding directly from the ComputedStyle
  RefPtr<ComputedStyle> sc =
    nsComputedDOMStyle::GetComputedStyleNoFlush(this, nullptr);
  NS_ENSURE_TRUE(sc, false);

  NS_IF_ADDREF(*aResult = sc->StyleDisplay()->mBinding);
  return true;
}

JSObject*
Element::WrapObject(JSContext *aCx, JS::Handle<JSObject*> aGivenProto)
{
  JS::Rooted<JSObject*> obj(aCx, nsINode::WrapObject(aCx, aGivenProto));
  if (!obj) {
    return nullptr;
  }

  nsIDocument* doc = GetComposedDoc();
  if (!doc) {
    // There's no baseclass that cares about this call so we just
    // return here.
    return obj;
  }

  // We must ensure that the XBL Binding is installed before we hand
  // back this object.

  if (HasFlag(NODE_MAY_BE_IN_BINDING_MNGR) && GetXBLBinding()) {
    // There's already a binding for this element so nothing left to
    // be done here.

    // In theory we could call ExecuteAttachedHandler here when it's safe to
    // run script if we also removed the binding from the PAQ queue, but that
    // seems like a scary change that would mosly just add more
    // inconsistencies.
    return obj;
  }

  // Make sure the ComputedStyle goes away _before_ we load the binding
  // since that can destroy the relevant presshell.

  {
    // Make a scope so that ~nsRefPtr can GC before returning obj.
    RefPtr<css::URLValue> bindingURL;
    bool ok = GetBindingURL(doc, getter_AddRefs(bindingURL));
    if (!ok) {
      dom::Throw(aCx, NS_ERROR_FAILURE);
      return nullptr;
    }

    if (bindingURL) {
      nsCOMPtr<nsIURI> uri = bindingURL->GetURI();
      nsCOMPtr<nsIPrincipal> principal = bindingURL->ExtraData()->Principal();

      // We have a binding that must be installed.
      bool dummy;

      nsXBLService* xblService = nsXBLService::GetInstance();
      if (!xblService) {
        dom::Throw(aCx, NS_ERROR_NOT_AVAILABLE);
        return nullptr;
      }

      RefPtr<nsXBLBinding> binding;
      xblService->LoadBindings(this, uri, principal, getter_AddRefs(binding),
                               &dummy);

      if (binding) {
        if (nsContentUtils::IsSafeToRunScript()) {
          binding->ExecuteAttachedHandler();
        } else {
          nsContentUtils::AddScriptRunner(
            NewRunnableMethod("nsXBLBinding::ExecuteAttachedHandler",
                              binding,
                              &nsXBLBinding::ExecuteAttachedHandler));
        }
      }
    }
  }

  return obj;
}

/* virtual */
nsINode*
Element::GetScopeChainParent() const
{
  return OwnerDoc();
}

nsDOMTokenList*
Element::ClassList()
{
  Element::nsDOMSlots* slots = DOMSlots();

  if (!slots->mClassList) {
    slots->mClassList = new nsDOMTokenList(this, nsGkAtoms::_class);
  }

  return slots->mClassList;
}

void
Element::GetAttributeNames(nsTArray<nsString>& aResult)
{
  uint32_t count = mAttrs.AttrCount();
  for (uint32_t i = 0; i < count; ++i) {
    const nsAttrName* name = mAttrs.AttrNameAt(i);
    name->GetQualifiedName(*aResult.AppendElement());
  }
}

already_AddRefed<nsIHTMLCollection>
Element::GetElementsByTagName(const nsAString& aLocalName)
{
  return NS_GetContentList(this, kNameSpaceID_Unknown, aLocalName);
}

nsIScrollableFrame*
Element::GetScrollFrame(nsIFrame **aFrame, FlushType aFlushType)
{
  // it isn't clear what to return for SVG nodes, so just return nothing
  if (IsSVGElement()) {
    if (aFrame) {
      *aFrame = nullptr;
    }
    return nullptr;
  }

  nsIFrame* frame = GetPrimaryFrame(aFlushType);
  if (aFrame) {
    *aFrame = frame;
  }
  if (frame) {
    // menu frames implement GetScrollTargetFrame but we don't want
    // to use it here.  Similar for comboboxes.
    LayoutFrameType type = frame->Type();
    if (type != LayoutFrameType::Menu &&
        type != LayoutFrameType::ComboboxControl) {
      nsIScrollableFrame *scrollFrame = frame->GetScrollTargetFrame();
      if (scrollFrame) {
        MOZ_ASSERT(!OwnerDoc()->IsScrollingElement(this),
                   "How can we have a scrollframe if we're the "
                   "scrollingElement for our document?");
        return scrollFrame;
      }
    }
  }

  nsIDocument* doc = OwnerDoc();
  // Note: This IsScrollingElement() call can flush frames, if we're the body of
  // a quirks mode document.
  bool isScrollingElement = OwnerDoc()->IsScrollingElement(this);
  // Now reget *aStyledFrame if the caller asked for it, because that frame
  // flush can kill it.
  if (aFrame) {
    *aFrame = GetPrimaryFrame(FlushType::None);
  }

  if (isScrollingElement) {
    // Our scroll info should map to the root scrollable frame if there is one.
    if (nsIPresShell* shell = doc->GetShell()) {
      return shell->GetRootScrollFrameAsScrollable();
    }
  }

  return nullptr;
}

void
Element::ScrollIntoView(const BooleanOrScrollIntoViewOptions& aObject)
{
  if (aObject.IsScrollIntoViewOptions()) {
    return ScrollIntoView(aObject.GetAsScrollIntoViewOptions());
  }

  MOZ_DIAGNOSTIC_ASSERT(aObject.IsBoolean());

  ScrollIntoViewOptions options;
  if (aObject.GetAsBoolean()) {
    options.mBlock = ScrollLogicalPosition::Start;
    options.mInline = ScrollLogicalPosition::Nearest;
  } else {
    options.mBlock = ScrollLogicalPosition::End;
    options.mInline = ScrollLogicalPosition::Nearest;
  }
  return ScrollIntoView(options);
}

void
Element::ScrollIntoView(const ScrollIntoViewOptions &aOptions)
{
  nsIDocument *document = GetComposedDoc();
  if (!document) {
    return;
  }

  // Get the presentation shell
  nsCOMPtr<nsIPresShell> presShell = document->GetShell();
  if (!presShell) {
    return;
  }

  int16_t vpercent = nsIPresShell::SCROLL_CENTER;
  switch (aOptions.mBlock) {
    case ScrollLogicalPosition::Start:
      vpercent = nsIPresShell::SCROLL_TOP;
      break;
    case ScrollLogicalPosition::Center:
      vpercent = nsIPresShell::SCROLL_CENTER;
      break;
    case ScrollLogicalPosition::End:
      vpercent = nsIPresShell::SCROLL_BOTTOM;
      break;
    case ScrollLogicalPosition::Nearest:
      vpercent = nsIPresShell::SCROLL_MINIMUM;
      break;
    default:
      MOZ_ASSERT_UNREACHABLE("Unexpected ScrollLogicalPosition value");
  }

  int16_t hpercent = nsIPresShell::SCROLL_CENTER;
  switch (aOptions.mInline) {
    case ScrollLogicalPosition::Start:
      hpercent = nsIPresShell::SCROLL_LEFT;
      break;
    case ScrollLogicalPosition::Center:
      hpercent = nsIPresShell::SCROLL_CENTER;
      break;
    case ScrollLogicalPosition::End:
      hpercent = nsIPresShell::SCROLL_RIGHT;
      break;
    case ScrollLogicalPosition::Nearest:
      hpercent = nsIPresShell::SCROLL_MINIMUM;
      break;
    default:
      MOZ_ASSERT_UNREACHABLE("Unexpected ScrollLogicalPosition value");
  }

  uint32_t flags = nsIPresShell::SCROLL_OVERFLOW_HIDDEN;
  if (aOptions.mBehavior == ScrollBehavior::Smooth) {
    flags |= nsIPresShell::SCROLL_SMOOTH;
  } else if (aOptions.mBehavior == ScrollBehavior::Auto) {
    flags |= nsIPresShell::SCROLL_SMOOTH_AUTO;
  }

  presShell->ScrollContentIntoView(this,
                                   nsIPresShell::ScrollAxis(
                                     vpercent,
                                     nsIPresShell::SCROLL_ALWAYS),
                                   nsIPresShell::ScrollAxis(
                                     hpercent,
                                     nsIPresShell::SCROLL_ALWAYS),
                                   flags);
}

void
Element::Scroll(const CSSIntPoint& aScroll, const ScrollOptions& aOptions)
{
  nsIScrollableFrame* sf = GetScrollFrame();
  if (sf) {
    nsIScrollableFrame::ScrollMode scrollMode = nsIScrollableFrame::INSTANT;
    if (aOptions.mBehavior == ScrollBehavior::Smooth) {
      scrollMode = nsIScrollableFrame::SMOOTH_MSD;
    } else if (aOptions.mBehavior == ScrollBehavior::Auto) {
      ScrollStyles styles = sf->GetScrollStyles();
      if (styles.mScrollBehavior == NS_STYLE_SCROLL_BEHAVIOR_SMOOTH) {
        scrollMode = nsIScrollableFrame::SMOOTH_MSD;
      }
    }

    sf->ScrollToCSSPixels(aScroll, scrollMode);
  }
}

void
Element::Scroll(double aXScroll, double aYScroll)
{
  // Convert -Inf, Inf, and NaN to 0; otherwise, convert by C-style cast.
  auto scrollPos = CSSIntPoint::Truncate(mozilla::ToZeroIfNonfinite(aXScroll),
                                         mozilla::ToZeroIfNonfinite(aYScroll));

  Scroll(scrollPos, ScrollOptions());
}

void
Element::Scroll(const ScrollToOptions& aOptions)
{
  nsIScrollableFrame *sf = GetScrollFrame();
  if (sf) {
    CSSIntPoint scrollPos = sf->GetScrollPositionCSSPixels();
    if (aOptions.mLeft.WasPassed()) {
      scrollPos.x = mozilla::ToZeroIfNonfinite(aOptions.mLeft.Value());
    }
    if (aOptions.mTop.WasPassed()) {
      scrollPos.y = mozilla::ToZeroIfNonfinite(aOptions.mTop.Value());
    }
    Scroll(scrollPos, aOptions);
  }
}

void
Element::ScrollTo(double aXScroll, double aYScroll)
{
  Scroll(aXScroll, aYScroll);
}

void
Element::ScrollTo(const ScrollToOptions& aOptions)
{
  Scroll(aOptions);
}

void
Element::ScrollBy(double aXScrollDif, double aYScrollDif)
{
  nsIScrollableFrame *sf = GetScrollFrame();
  if (sf) {
    ScrollToOptions options;
    options.mLeft.Construct(aXScrollDif);
    options.mTop.Construct(aYScrollDif);
    ScrollBy(options);
  }
}

void
Element::ScrollBy(const ScrollToOptions& aOptions)
{
  nsIScrollableFrame *sf = GetScrollFrame();
  if (sf) {
    CSSIntPoint scrollDelta;
    if (aOptions.mLeft.WasPassed()) {
      scrollDelta.x = mozilla::ToZeroIfNonfinite(aOptions.mLeft.Value());
    }
    if (aOptions.mTop.WasPassed()) {
      scrollDelta.y = mozilla::ToZeroIfNonfinite(aOptions.mTop.Value());
    }

    nsIScrollableFrame::ScrollMode scrollMode = nsIScrollableFrame::INSTANT;
    if (aOptions.mBehavior == ScrollBehavior::Smooth) {
      scrollMode = nsIScrollableFrame::SMOOTH_MSD;
    } else if (aOptions.mBehavior == ScrollBehavior::Auto) {
      ScrollStyles styles = sf->GetScrollStyles();
      if (styles.mScrollBehavior == NS_STYLE_SCROLL_BEHAVIOR_SMOOTH) {
        scrollMode = nsIScrollableFrame::SMOOTH_MSD;
      }
    }

    sf->ScrollByCSSPixels(scrollDelta, scrollMode, nsGkAtoms::relative);
  }
}

int32_t
Element::ScrollTop()
{
  nsIScrollableFrame* sf = GetScrollFrame();
  return sf ? sf->GetScrollPositionCSSPixels().y : 0;
}

void
Element::SetScrollTop(int32_t aScrollTop)
{
  // When aScrollTop is 0, we don't need to flush layout to scroll to that
  // point; we know 0 is always in range.  At least we think so...  But we do
  // need to flush frames so we ensure we find the right scrollable frame if
  // there is one.
  //
  // If aScrollTop is nonzero, we need to flush layout because we need to figure
  // out what our real scrollTopMax is.
  FlushType flushType = aScrollTop == 0 ? FlushType::Frames : FlushType::Layout;
  nsIScrollableFrame* sf = GetScrollFrame(nullptr, flushType);
  if (sf) {
    nsIScrollableFrame::ScrollMode scrollMode = nsIScrollableFrame::INSTANT;
    if (sf->GetScrollStyles().mScrollBehavior == NS_STYLE_SCROLL_BEHAVIOR_SMOOTH) {
      scrollMode = nsIScrollableFrame::SMOOTH_MSD;
    }
    sf->ScrollToCSSPixels(CSSIntPoint(sf->GetScrollPositionCSSPixels().x,
                                      aScrollTop),
                          scrollMode);
  }
}

int32_t
Element::ScrollLeft()
{
  nsIScrollableFrame* sf = GetScrollFrame();
  return sf ? sf->GetScrollPositionCSSPixels().x : 0;
}

void
Element::SetScrollLeft(int32_t aScrollLeft)
{
  // We can't assume things here based on the value of aScrollLeft, because
  // depending on our direction and layout 0 may or may not be in our scroll
  // range.  So we need to flush layout no matter what.
  nsIScrollableFrame* sf = GetScrollFrame();
  if (sf) {
    nsIScrollableFrame::ScrollMode scrollMode = nsIScrollableFrame::INSTANT;
    if (sf->GetScrollStyles().mScrollBehavior == NS_STYLE_SCROLL_BEHAVIOR_SMOOTH) {
      scrollMode = nsIScrollableFrame::SMOOTH_MSD;
    }

    sf->ScrollToCSSPixels(CSSIntPoint(aScrollLeft,
                                      sf->GetScrollPositionCSSPixels().y),
                          scrollMode);
  }
}


bool
Element::ScrollByNoFlush(int32_t aDx, int32_t aDy)
{
  nsIScrollableFrame* sf = GetScrollFrame(nullptr, FlushType::None);
  if (!sf) {
    return false;
  }

  AutoWeakFrame weakRef(sf->GetScrolledFrame());

  CSSIntPoint before = sf->GetScrollPositionCSSPixels();
  sf->ScrollToCSSPixelsApproximate(CSSIntPoint(before.x + aDx, before.y + aDy));

  // The frame was destroyed, can't keep on scrolling.
  if (!weakRef.IsAlive()) {
    return false;
  }

  CSSIntPoint after = sf->GetScrollPositionCSSPixels();
  return (before != after);
}

void
Element::MozScrollSnap()
{
  nsIScrollableFrame* sf = GetScrollFrame(nullptr, FlushType::None);
  if (sf) {
    sf->ScrollSnap();
  }
}

static nsSize GetScrollRectSizeForOverflowVisibleFrame(nsIFrame* aFrame)
{
  if (!aFrame) {
    return nsSize(0,0);
  }

  nsRect paddingRect = aFrame->GetPaddingRectRelativeToSelf();
  nsOverflowAreas overflowAreas(paddingRect, paddingRect);
  // Add the scrollable overflow areas of children (if any) to the paddingRect.
  // It's important to start with the paddingRect, otherwise if there are no
  // children the overflow rect will be 0,0,0,0 which will force the point 0,0
  // to be included in the final rect.
  nsLayoutUtils::UnionChildOverflow(aFrame, overflowAreas);
  // Make sure that an empty padding-rect's edges are included, by adding
  // the padding-rect in again with UnionEdges.
  nsRect overflowRect =
    overflowAreas.ScrollableOverflow().UnionEdges(paddingRect);
  return nsLayoutUtils::GetScrolledRect(aFrame,
      overflowRect, paddingRect.Size(),
      aFrame->StyleVisibility()->mDirection).Size();
}

int32_t
Element::ScrollHeight()
{
  if (IsSVGElement())
    return 0;

  nsIFrame* frame;
  nsIScrollableFrame* sf = GetScrollFrame(&frame);
  nscoord height;
  if (sf) {
    height = sf->GetScrollRange().Height() + sf->GetScrollPortRect().Height();
  } else {
    height = GetScrollRectSizeForOverflowVisibleFrame(frame).height;
  }

  return nsPresContext::AppUnitsToIntCSSPixels(height);
}

int32_t
Element::ScrollWidth()
{
  if (IsSVGElement())
    return 0;

  nsIFrame* frame;
  nsIScrollableFrame* sf = GetScrollFrame(&frame);
  nscoord width;
  if (sf) {
    width = sf->GetScrollRange().Width() + sf->GetScrollPortRect().Width();
  } else {
    width = GetScrollRectSizeForOverflowVisibleFrame(frame).width;
  }

  return nsPresContext::AppUnitsToIntCSSPixels(width);
}

nsRect
Element::GetClientAreaRect()
{
  nsIFrame* frame;
  nsIScrollableFrame* sf = GetScrollFrame(&frame);

  if (sf) {
    return sf->GetScrollPortRect();
  }

  if (frame &&
      // The display check is OK even though we're not looking at the style
      // frame, because the style frame only differs from "frame" for tables,
      // and table wrappers have the same display as the table itself.
      (frame->StyleDisplay()->mDisplay != StyleDisplay::Inline ||
       frame->IsFrameOfType(nsIFrame::eReplaced))) {
    // Special case code to make client area work even when there isn't
    // a scroll view, see bug 180552, bug 227567.
    return frame->GetPaddingRect() - frame->GetPositionIgnoringScrolling();
  }

  // SVG nodes reach here and just return 0
  return nsRect(0, 0, 0, 0);
}

already_AddRefed<DOMRect>
Element::GetBoundingClientRect()
{
  RefPtr<DOMRect> rect = new DOMRect(this);

  nsIFrame* frame = GetPrimaryFrame(FlushType::Layout);
  if (!frame) {
    // display:none, perhaps? Return the empty rect
    return rect.forget();
  }

  nsRect r = nsLayoutUtils::GetAllInFlowRectsUnion(frame,
          nsLayoutUtils::GetContainingBlockForClientRect(frame),
          nsLayoutUtils::RECTS_ACCOUNT_FOR_TRANSFORMS);
  rect->SetLayoutRect(r);
  return rect.forget();
}

already_AddRefed<DOMRectList>
Element::GetClientRects()
{
  RefPtr<DOMRectList> rectList = new DOMRectList(this);

  nsIFrame* frame = GetPrimaryFrame(FlushType::Layout);
  if (!frame) {
    // display:none, perhaps? Return an empty list
    return rectList.forget();
  }

  nsLayoutUtils::RectListBuilder builder(rectList);
  nsLayoutUtils::GetAllInFlowRects(frame,
          nsLayoutUtils::GetContainingBlockForClientRect(frame), &builder,
          nsLayoutUtils::RECTS_ACCOUNT_FOR_TRANSFORMS);
  return rectList.forget();
}

//----------------------------------------------------------------------

void
Element::AddToIdTable(nsAtom* aId)
{
  NS_ASSERTION(HasID(), "Node doesn't have an ID?");
  if (IsInShadowTree()) {
    ShadowRoot* containingShadow = GetContainingShadow();
    containingShadow->AddToIdTable(this, aId);
  } else {
    nsIDocument* doc = GetUncomposedDoc();
    if (doc && !IsInAnonymousSubtree()) {
      doc->AddToIdTable(this, aId);
    }
  }
}

void
Element::RemoveFromIdTable()
{
  if (!HasID()) {
    return;
  }

  nsAtom* id = DoGetID();
  if (IsInShadowTree()) {
    ShadowRoot* containingShadow = GetContainingShadow();
    // Check for containingShadow because it may have
    // been deleted during unlinking.
    if (containingShadow) {
      containingShadow->RemoveFromIdTable(this, id);
    }
  } else {
    nsIDocument* doc = GetUncomposedDoc();
    if (doc && !IsInAnonymousSubtree()) {
      doc->RemoveFromIdTable(this, id);
    }
  }
}

void
Element::SetSlot(const nsAString& aName, ErrorResult& aError)
{
  aError = SetAttr(kNameSpaceID_None, nsGkAtoms::slot, aName, true);
}

void
Element::GetSlot(nsAString& aName)
{
  GetAttr(kNameSpaceID_None, nsGkAtoms::slot, aName);
}

// https://dom.spec.whatwg.org/#dom-element-shadowroot
ShadowRoot*
Element::GetShadowRootByMode() const
{
  /**
   * 1. Let shadow be context object’s shadow root.
   * 2. If shadow is null or its mode is "closed", then return null.
   */
  ShadowRoot* shadowRoot = GetShadowRoot();
  if (!shadowRoot || shadowRoot->IsClosed()) {
    return nullptr;
  }

  /**
   * 3. Return shadow.
   */
  return shadowRoot;
}

bool
Element::CanAttachShadowDOM() const
{
  /**
   * If context object’s local name is not
   *    a valid custom element name, "article", "aside", "blockquote",
   *    "body", "div", "footer", "h1", "h2", "h3", "h4", "h5", "h6",
   *    "header", "main" "nav", "p", "section", or "span",
   *  return false.
   */
  nsAtom* nameAtom = NodeInfo()->NameAtom();
  if (!(nsContentUtils::IsCustomElementName(nameAtom, NodeInfo()->NamespaceID()) ||
        nameAtom == nsGkAtoms::article ||
        nameAtom == nsGkAtoms::aside ||
        nameAtom == nsGkAtoms::blockquote ||
        nameAtom == nsGkAtoms::body ||
        nameAtom == nsGkAtoms::div ||
        nameAtom == nsGkAtoms::footer ||
        nameAtom == nsGkAtoms::h1 ||
        nameAtom == nsGkAtoms::h2 ||
        nameAtom == nsGkAtoms::h3 ||
        nameAtom == nsGkAtoms::h4 ||
        nameAtom == nsGkAtoms::h5 ||
        nameAtom == nsGkAtoms::h6 ||
        nameAtom == nsGkAtoms::header ||
        nameAtom == nsGkAtoms::main ||
        nameAtom == nsGkAtoms::nav ||
        nameAtom == nsGkAtoms::p ||
        nameAtom == nsGkAtoms::section ||
        nameAtom == nsGkAtoms::span)) {
    return false;
  }

  return true;
}

// https://dom.spec.whatwg.org/#dom-element-attachshadow
already_AddRefed<ShadowRoot>
Element::AttachShadow(const ShadowRootInit& aInit, ErrorResult& aError)
{
  /**
   * 1. If context object’s namespace is not the HTML namespace,
   *    then throw a "NotSupportedError" DOMException.
   */
  if (!IsHTMLElement() &&
      !(XRE_IsParentProcess() && IsXULElement() && nsContentUtils::AllowXULXBLForPrincipal(NodePrincipal()))) {
    aError.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
    return nullptr;
  }

  /**
   * 2. If context object’s local name is not valid to attach shadow DOM to,
   *    then throw a "NotSupportedError" DOMException.
   */
  if (!CanAttachShadowDOM()) {
    aError.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
    return nullptr;
  }

  /**
   * 2. If context object is a shadow host, then throw
   *    an "InvalidStateError" DOMException.
   */
  if (GetShadowRoot() || GetXBLBinding()) {
    aError.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
    return nullptr;
  }

  if (StaticPrefs::dom_webcomponents_shadowdom_report_usage()) {
    OwnerDoc()->ReportShadowDOMUsage();
  }

  return AttachShadowWithoutNameChecks(aInit.mMode);
}

already_AddRefed<ShadowRoot>
Element::AttachShadowWithoutNameChecks(ShadowRootMode aMode)
{
  nsAutoScriptBlocker scriptBlocker;

  RefPtr<mozilla::dom::NodeInfo> nodeInfo =
    mNodeInfo->NodeInfoManager()->GetNodeInfo(
      nsGkAtoms::documentFragmentNodeName, nullptr, kNameSpaceID_None,
      DOCUMENT_FRAGMENT_NODE);

  if (nsIDocument* doc = GetComposedDoc()) {
    if (nsIPresShell* shell = doc->GetShell()) {
      shell->DestroyFramesForAndRestyle(this);
    }
  }
  MOZ_ASSERT(!GetPrimaryFrame());

  /**
   * 4. Let shadow be a new shadow root whose node document is
   *    context object’s node document, host is context object,
   *    and mode is init’s mode.
   */
  RefPtr<ShadowRoot> shadowRoot =
    new ShadowRoot(this, aMode, nodeInfo.forget());

  if (NodeOrAncestorHasDirAuto()) {
    shadowRoot->SetAncestorHasDirAuto();
  }

  /**
   * 5. Set context object’s shadow root to shadow.
   */
  SetShadowRoot(shadowRoot);

  // Dispatch a "shadowrootattached" event for devtools.
  {
    AsyncEventDispatcher* dispatcher =
      new AsyncEventDispatcher(this,
                               NS_LITERAL_STRING("shadowrootattached"),
                               CanBubble::eYes,
                               ChromeOnlyDispatch::eYes,
                               Composed::eYes);
    dispatcher->PostDOMEvent();
  }

  /**
   * 6. Return shadow.
   */
  return shadowRoot.forget();
}

void
Element::UnattachShadow()
{
  ShadowRoot* shadowRoot = GetShadowRoot();
  if (!shadowRoot) {
    return;
  }

  nsAutoScriptBlocker scriptBlocker;

  if (nsIDocument* doc = GetComposedDoc()) {
    if (nsIPresShell* shell = doc->GetShell()) {
      shell->DestroyFramesForAndRestyle(this);
    }
  }
  MOZ_ASSERT(!GetPrimaryFrame());

  shadowRoot->Unattach();
  SetShadowRoot(nullptr);

  // Beware shadowRoot could be dead after this call.
}

void
Element::GetAttribute(const nsAString& aName, DOMString& aReturn)
{
  const nsAttrValue* val =
    mAttrs.GetAttr(aName,
                   IsHTMLElement() && IsInHTMLDocument() ?
                     eIgnoreCase : eCaseMatters);
  if (val) {
    val->ToString(aReturn);
  } else {
    if (IsXULElement()) {
      // XXX should be SetDOMStringToNull(aReturn);
      // See bug 232598
      // aReturn is already empty
    } else {
      aReturn.SetNull();
    }
  }
}

bool
Element::ToggleAttribute(const nsAString& aName,
                         const Optional<bool>& aForce,
                         nsIPrincipal* aTriggeringPrincipal,
                         ErrorResult& aError)
{
  aError = nsContentUtils::CheckQName(aName, false);
  if (aError.Failed()) {
    return false;
  }

  nsAutoString nameToUse;
  const nsAttrName* name = InternalGetAttrNameFromQName(aName, &nameToUse);
  if (!name) {
    if (aForce.WasPassed() && !aForce.Value()) {
      return false;
    }
    RefPtr<nsAtom> nameAtom = NS_AtomizeMainThread(nameToUse);
    if (!nameAtom) {
      aError.Throw(NS_ERROR_OUT_OF_MEMORY);
      return false;
    }
    aError = SetAttr(kNameSpaceID_None, nameAtom, EmptyString(), aTriggeringPrincipal, true);
    return true;
  }
  if (aForce.WasPassed() && aForce.Value()) {
    return true;
  }
  // Hold a strong reference here so that the atom or nodeinfo doesn't go
  // away during UnsetAttr. If it did UnsetAttr would be left with a
  // dangling pointer as argument without knowing it.
  nsAttrName tmp(*name);

  aError = UnsetAttr(name->NamespaceID(), name->LocalName(), true);
  return false;
}

void
Element::SetAttribute(const nsAString& aName,
                      const nsAString& aValue,
                      nsIPrincipal* aTriggeringPrincipal,
                      ErrorResult& aError)
{
  aError = nsContentUtils::CheckQName(aName, false);
  if (aError.Failed()) {
    return;
  }

  nsAutoString nameToUse;
  const nsAttrName* name = InternalGetAttrNameFromQName(aName, &nameToUse);
  if (!name) {
    RefPtr<nsAtom> nameAtom = NS_AtomizeMainThread(nameToUse);
    if (!nameAtom) {
      aError.Throw(NS_ERROR_OUT_OF_MEMORY);
      return;
    }
    aError = SetAttr(kNameSpaceID_None, nameAtom, aValue, aTriggeringPrincipal, true);
    return;
  }

  aError = SetAttr(name->NamespaceID(), name->LocalName(), name->GetPrefix(),
                   aValue, aTriggeringPrincipal, true);
}

void
Element::RemoveAttribute(const nsAString& aName, ErrorResult& aError)
{
  const nsAttrName* name = InternalGetAttrNameFromQName(aName);

  if (!name) {
    // If there is no canonical nsAttrName for this attribute name, then the
    // attribute does not exist and we can't get its namespace ID and
    // local name below, so we return early.
    return;
  }

  // Hold a strong reference here so that the atom or nodeinfo doesn't go
  // away during UnsetAttr. If it did UnsetAttr would be left with a
  // dangling pointer as argument without knowing it.
  nsAttrName tmp(*name);

  aError = UnsetAttr(name->NamespaceID(), name->LocalName(), true);
}

Attr*
Element::GetAttributeNode(const nsAString& aName)
{
  return Attributes()->GetNamedItem(aName);
}

already_AddRefed<Attr>
Element::SetAttributeNode(Attr& aNewAttr, ErrorResult& aError)
{
  return Attributes()->SetNamedItemNS(aNewAttr, aError);
}

already_AddRefed<Attr>
Element::RemoveAttributeNode(Attr& aAttribute,
                             ErrorResult& aError)
{
  Element *elem = aAttribute.GetElement();
  if (elem != this) {
    aError.Throw(NS_ERROR_DOM_NOT_FOUND_ERR);
    return nullptr;
  }

  nsAutoString nameSpaceURI;
  aAttribute.NodeInfo()->GetNamespaceURI(nameSpaceURI);
  return Attributes()->RemoveNamedItemNS(nameSpaceURI, aAttribute.NodeInfo()->LocalName(), aError);
}

void
Element::GetAttributeNS(const nsAString& aNamespaceURI,
                        const nsAString& aLocalName,
                        nsAString& aReturn)
{
  int32_t nsid =
    nsContentUtils::NameSpaceManager()->GetNameSpaceID(aNamespaceURI,
                                                       nsContentUtils::IsChromeDoc(OwnerDoc()));

  if (nsid == kNameSpaceID_Unknown) {
    // Unknown namespace means no attribute.
    SetDOMStringToNull(aReturn);
    return;
  }

  RefPtr<nsAtom> name = NS_AtomizeMainThread(aLocalName);
  bool hasAttr = GetAttr(nsid, name, aReturn);
  if (!hasAttr) {
    SetDOMStringToNull(aReturn);
  }
}

void
Element::SetAttributeNS(const nsAString& aNamespaceURI,
                        const nsAString& aQualifiedName,
                        const nsAString& aValue,
                        nsIPrincipal* aTriggeringPrincipal,
                        ErrorResult& aError)
{
  RefPtr<mozilla::dom::NodeInfo> ni;
  aError =
    nsContentUtils::GetNodeInfoFromQName(aNamespaceURI, aQualifiedName,
                                         mNodeInfo->NodeInfoManager(),
                                         ATTRIBUTE_NODE,
                                         getter_AddRefs(ni));
  if (aError.Failed()) {
    return;
  }

  aError = SetAttr(ni->NamespaceID(), ni->NameAtom(), ni->GetPrefixAtom(),
                   aValue, aTriggeringPrincipal, true);
}

void
Element::RemoveAttributeNS(const nsAString& aNamespaceURI,
                           const nsAString& aLocalName,
                           ErrorResult& aError)
{
  RefPtr<nsAtom> name = NS_AtomizeMainThread(aLocalName);
  int32_t nsid =
    nsContentUtils::NameSpaceManager()->GetNameSpaceID(aNamespaceURI,
                                                       nsContentUtils::IsChromeDoc(OwnerDoc()));

  if (nsid == kNameSpaceID_Unknown) {
    // If the namespace ID is unknown, it means there can't possibly be an
    // existing attribute. We would need a known namespace ID to pass into
    // UnsetAttr, so we return early if we don't have one.
    return;
  }

  aError = UnsetAttr(nsid, name, true);
}

Attr*
Element::GetAttributeNodeNS(const nsAString& aNamespaceURI,
                            const nsAString& aLocalName)
{
  return GetAttributeNodeNSInternal(aNamespaceURI, aLocalName);
}

Attr*
Element::GetAttributeNodeNSInternal(const nsAString& aNamespaceURI,
                                    const nsAString& aLocalName)
{
  return Attributes()->GetNamedItemNS(aNamespaceURI, aLocalName);
}

already_AddRefed<Attr>
Element::SetAttributeNodeNS(Attr& aNewAttr,
                            ErrorResult& aError)
{
  return Attributes()->SetNamedItemNS(aNewAttr, aError);
}

already_AddRefed<nsIHTMLCollection>
Element::GetElementsByTagNameNS(const nsAString& aNamespaceURI,
                                const nsAString& aLocalName,
                                ErrorResult& aError)
{
  int32_t nameSpaceId = kNameSpaceID_Wildcard;

  if (!aNamespaceURI.EqualsLiteral("*")) {
    aError =
      nsContentUtils::NameSpaceManager()->RegisterNameSpace(aNamespaceURI,
                                                            nameSpaceId);
    if (aError.Failed()) {
      return nullptr;
    }
  }

  NS_ASSERTION(nameSpaceId != kNameSpaceID_Unknown, "Unexpected namespace ID!");

  return NS_GetContentList(this, nameSpaceId, aLocalName);
}

bool
Element::HasAttributeNS(const nsAString& aNamespaceURI,
                        const nsAString& aLocalName) const
{
  int32_t nsid =
    nsContentUtils::NameSpaceManager()->GetNameSpaceID(aNamespaceURI,
                                                       nsContentUtils::IsChromeDoc(OwnerDoc()));

  if (nsid == kNameSpaceID_Unknown) {
    // Unknown namespace means no attr...
    return false;
  }

  RefPtr<nsAtom> name = NS_AtomizeMainThread(aLocalName);
  return HasAttr(nsid, name);
}

already_AddRefed<nsIHTMLCollection>
Element::GetElementsByClassName(const nsAString& aClassNames)
{
  return nsContentUtils::GetElementsByClassName(this, aClassNames);
}

void
Element::GetElementsWithGrid(nsTArray<RefPtr<Element>>& aElements)
{
  nsINode* cur = this;
  while (cur) {
    if (cur->IsElement()) {
      Element* elem = cur->AsElement();

      if (elem->GetPrimaryFrame()) {
        // See if this has a GridContainerFrame. Use the same method that
        // nsGridContainerFrame uses, which deals with some edge cases.
        if (nsGridContainerFrame::GetGridContainerFrame(elem->GetPrimaryFrame())) {
          aElements.AppendElement(elem);
        }

        // This element has a frame, so allow the traversal to go through
        // the children.
        cur = cur->GetNextNode(this);
        continue;
      }
    }

    // Either this isn't an element, or it has no frame. Continue with the
    // traversal but ignore all the children.
    cur = cur->GetNextNonChildNode(this);
  }
}

/**
 * Returns the count of descendants (inclusive of aContent) in
 * the uncomposed document that are explicitly set as editable.
 */
static uint32_t
EditableInclusiveDescendantCount(nsIContent* aContent)
{
  auto htmlElem = nsGenericHTMLElement::FromNode(aContent);
  if (htmlElem) {
    return htmlElem->EditableInclusiveDescendantCount();
  }

  return aContent->EditableDescendantCount();
}

nsresult
Element::BindToTree(nsIDocument* aDocument, nsIContent* aParent,
                    nsIContent* aBindingParent)
{
  MOZ_ASSERT(aParent || aDocument, "Must have document if no parent!");
  MOZ_ASSERT((NODE_FROM(aParent, aDocument)->OwnerDoc() == OwnerDoc()),
             "Must have the same owner document");
  MOZ_ASSERT(!aParent || aDocument == aParent->GetUncomposedDoc(),
             "aDocument must be current doc of aParent");
  MOZ_ASSERT(!IsInComposedDoc(), "Already have a document.  Unbind first!");
  MOZ_ASSERT(!IsInUncomposedDoc(), "Already have a document.  Unbind first!");
  // Note that as we recurse into the kids, they'll have a non-null parent.  So
  // only assert if our parent is _changing_ while we have a parent.
  MOZ_ASSERT(!GetParent() || aParent == GetParent(),
             "Already have a parent.  Unbind first!");
  MOZ_ASSERT(!GetBindingParent() ||
             aBindingParent == GetBindingParent() ||
             (!aBindingParent && aParent &&
              aParent->GetBindingParent() == GetBindingParent()),
             "Already have a binding parent.  Unbind first!");
  MOZ_ASSERT(aBindingParent != this,
             "Content must not be its own binding parent");
  MOZ_ASSERT(!IsRootOfNativeAnonymousSubtree() ||
             aBindingParent == aParent,
             "Native anonymous content must have its parent as its "
             "own binding parent");
  MOZ_ASSERT(aBindingParent || !aParent ||
             aBindingParent == aParent->GetBindingParent(),
             "We should be passed the right binding parent");

#ifdef MOZ_XUL
  // First set the binding parent
  nsXULElement* xulElem = nsXULElement::FromNode(this);
  if (xulElem) {
    xulElem->SetXULBindingParent(aBindingParent);
  }
  else
#endif
  {
    if (aBindingParent) {
      nsExtendedDOMSlots* slots = ExtendedDOMSlots();

      slots->mBindingParent = aBindingParent; // Weak, so no addref happens.
    }
  }

  const bool hadParent = !!GetParentNode();
  const bool wasInShadowTree = IsInShadowTree();

  NS_ASSERTION(!aBindingParent || IsRootOfNativeAnonymousSubtree() ||
               !HasFlag(NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE) ||
               (aParent && aParent->IsInNativeAnonymousSubtree()),
               "Trying to re-bind content from native anonymous subtree to "
               "non-native anonymous parent!");
  if (aParent) {
    if (aParent->IsInNativeAnonymousSubtree()) {
      SetFlags(NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE);
    }
    if (aParent->HasFlag(NODE_CHROME_ONLY_ACCESS)) {
      SetFlags(NODE_CHROME_ONLY_ACCESS);
    }
    if (HasFlag(NODE_IS_ANONYMOUS_ROOT)) {
      aParent->SetMayHaveAnonymousChildren();
    }
    if (aParent->IsInShadowTree()) {
      ClearSubtreeRootPointer();
      SetFlags(NODE_IS_IN_SHADOW_TREE);
      MOZ_ASSERT(aParent->GetContainingShadow());
      ExtendedDOMSlots()->mContainingShadow = aParent->GetContainingShadow();
    }
  }

  MOZ_ASSERT_IF(wasInShadowTree, IsInShadowTree());

  // Now set the parent.
  if (aParent) {
    if (!GetParent()) {
      NS_ADDREF(aParent);
    }
    mParent = aParent;
  } else {
    mParent = aDocument;
  }
  SetParentIsContent(aParent);

  // XXXbz sXBL/XBL2 issue!

  MOZ_ASSERT(!HasAnyOfFlags(Element::kAllServoDescendantBits));

  // Finally, set the document
  if (aDocument) {
    // Notify XBL- & nsIAnonymousContentCreator-generated
    // anonymous content that the document is changing.
    // XXXbz ordering issues here?  Probably not, since ChangeDocumentFor is
    // just pretty broken anyway....  Need to get it working.
    // XXXbz XBL doesn't handle this (asserts), and we don't really want
    // to be doing this during parsing anyway... sort this out.
    //    aDocument->BindingManager()->ChangeDocumentFor(this, nullptr,
    //                                                   aDocument);

    // We no longer need to track the subtree pointer (and in fact we'll assert
    // if we do this any later).
    ClearSubtreeRootPointer();

    // Being added to a document.
    SetIsInDocument();
    SetIsConnected(true);

    // Clear the lazy frame construction bits.
    UnsetFlags(NODE_NEEDS_FRAME | NODE_DESCENDANTS_NEED_FRAMES);
  } else if (IsInShadowTree()) {
    SetIsConnected(aParent->IsInComposedDoc());
    // We're not in a document, but we did get inserted into a shadow tree.
    // Since we won't have any restyle data in the document's restyle trackers,
    // don't let us get inserted with restyle bits set incorrectly.
    //
    // Also clear all the other flags that are cleared above when we do get
    // inserted into a document.
    //
    // See the comment about the restyle bits above, it also applies.
    UnsetFlags(NODE_NEEDS_FRAME | NODE_DESCENDANTS_NEED_FRAMES);
  } else {
    // If we're not in the doc and not in a shadow tree,
    // update our subtree pointer.
    SetSubtreeRootPointer(aParent->SubtreeRoot());
  }

  if (CustomElementRegistry::IsCustomElementEnabled(OwnerDoc()) && IsInComposedDoc()) {
    // Connected callback must be enqueued whenever a custom element becomes
    // connected.
    CustomElementData* data = GetCustomElementData();
    if (data) {
      if (data->mState == CustomElementData::State::eCustom) {
        nsContentUtils::EnqueueLifecycleCallback(nsIDocument::eConnected, this);
      } else {
        // Step 7.7.2.2 https://dom.spec.whatwg.org/#concept-node-insert
        nsContentUtils::TryToUpgradeElement(this);
      }
    }
  }

  // This has to be here, rather than in nsGenericHTMLElement::BindToTree,
  //  because it has to happen after updating the parent pointer, but before
  //  recursively binding the kids.
  if (IsHTMLElement()) {
    SetDirOnBind(this, aParent);
  }

  uint32_t editableDescendantCount = 0;

  UpdateEditableState(false);

  // If we had a pre-existing XBL binding, we might have anonymous children that
  // also need to be told that they are moving.
  if (HasFlag(NODE_MAY_BE_IN_BINDING_MNGR)) {
    nsXBLBinding* binding =
      OwnerDoc()->BindingManager()->GetBindingWithContent(this);

    if (binding) {
      binding->BindAnonymousContent(
        binding->GetAnonymousContent(),
        this,
        binding->PrototypeBinding()->ChromeOnlyContent());
    }
  }

  // Now recurse into our kids
  nsresult rv;
  for (nsIContent* child = GetFirstChild(); child;
       child = child->GetNextSibling()) {
    rv = child->BindToTree(aDocument, this, aBindingParent);
    NS_ENSURE_SUCCESS(rv, rv);

    editableDescendantCount += EditableInclusiveDescendantCount(child);
  }

  if (aDocument) {
    // Update our editable descendant count because we don't keep track of it
    // for content that is not in the uncomposed document.
    MOZ_ASSERT(EditableDescendantCount() == 0);
    ChangeEditableDescendantCount(editableDescendantCount);

    if (!hadParent) {
      uint32_t editableDescendantChange = EditableInclusiveDescendantCount(this);
      if (editableDescendantChange != 0) {
        // If we are binding a subtree root to the document, we need to update
        // the editable descendant count of all the ancestors.
        // But we don't cross Shadow DOM boundary.
        // (The expected behavior with Shadow DOM is unclear)
        nsIContent* parent = GetParent();
        while (parent && parent->IsElement()) {
          parent->ChangeEditableDescendantCount(editableDescendantChange);
          parent = parent->GetParent();
        }
      }
    }
  }

  nsNodeUtils::ParentChainChanged(this);
  if (!hadParent && IsRootOfNativeAnonymousSubtree()) {
    nsNodeUtils::NativeAnonymousChildListChange(this, false);
  }

  // Ensure we only add to the table once, in the case we move the ShadowRoot
  // around.
  if (HasID() && !wasInShadowTree) {
    AddToIdTable(DoGetID());
  }

  if (MayHaveStyle() && !IsXULElement()) {
    // XXXbz if we already have a style attr parsed, this won't do
    // anything... need to fix that.
    // If MayHaveStyle() is true, we must be an nsStyledElement
    static_cast<nsStyledElement*>(this)->ReparseStyleAttribute(false, false);
  }

  // Call BindToTree on shadow root children.
  if (ShadowRoot* shadowRoot = GetShadowRoot()) {
    rv = shadowRoot->Bind();
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // FIXME(emilio): Why is this needed? The element shouldn't even be styled in
  // the first place, we should style it properly eventually.
  //
  // Also, if this _is_ needed, then it's wrong and should use GetComposedDoc()
  // to account for Shadow DOM.
  if (aDocument && MayHaveAnimations()) {
    CSSPseudoElementType pseudoType = GetPseudoElementType();
    if ((pseudoType == CSSPseudoElementType::NotPseudo ||
         pseudoType == CSSPseudoElementType::before ||
         pseudoType == CSSPseudoElementType::after) &&
        EffectSet::GetEffectSet(this, pseudoType)) {
      if (nsPresContext* presContext = aDocument->GetPresContext()) {
        presContext->EffectCompositor()->
          RequestRestyle(this, pseudoType,
                         EffectCompositor::RestyleType::Standard,
                         EffectCompositor::CascadeLevel::Animations);
      }
    }
  }

  // XXXbz script execution during binding can trigger some of these
  // postcondition asserts....  But we do want that, since things will
  // generally be quite broken when that happens.
  MOZ_ASSERT(aDocument == GetUncomposedDoc(), "Bound to wrong document");
  MOZ_ASSERT(aParent == GetParent(), "Bound to wrong parent");
  MOZ_ASSERT(aBindingParent == GetBindingParent(),
             "Bound to wrong binding parent");

  return NS_OK;
}

RemoveFromBindingManagerRunnable::RemoveFromBindingManagerRunnable(
  nsBindingManager* aManager,
  nsIContent* aContent,
  nsIDocument* aDoc)
  : mozilla::Runnable("dom::RemoveFromBindingManagerRunnable")
  , mManager(aManager)
  , mContent(aContent)
  , mDoc(aDoc)
{}

RemoveFromBindingManagerRunnable::~RemoveFromBindingManagerRunnable() {}

NS_IMETHODIMP
RemoveFromBindingManagerRunnable::Run()
{
  // It may be the case that the element was removed from the
  // DOM, causing this runnable to be created, then inserted back
  // into the document before the this runnable had a chance to
  // tear down the binding. Only tear down the binding if the element
  // is still no longer in the DOM. nsXBLService::LoadBinding tears
  // down the old binding if the element is inserted back into the
  // DOM and loads a different binding.
  if (!mContent->IsInComposedDoc()) {
    mManager->RemovedFromDocumentInternal(mContent, mDoc,
                                          nsBindingManager::eRunDtor);
  }

  return NS_OK;
}

static bool
ShouldRemoveFromIdTableOnUnbind(const Element& aElement, bool aNullParent)
{
  if (aElement.IsInUncomposedDoc()) {
    return true;
  }

  if (!aElement.IsInShadowTree()) {
    return false;
  }

  return aNullParent || !aElement.GetParent()->IsInShadowTree();
}

void
Element::UnbindFromTree(bool aDeep, bool aNullParent)
{
  MOZ_ASSERT(aDeep || (!GetUncomposedDoc() && !GetBindingParent()),
                  "Shallow unbind won't clear document and binding parent on "
                  "kids!");

  // Make sure to only remove from the ID table if our subtree root is actually
  // changing.
  if (ShouldRemoveFromIdTableOnUnbind(*this, aNullParent)) {
    RemoveFromIdTable();
  }

  // Make sure to unbind this node before doing the kids
  nsIDocument* document = GetComposedDoc();

  if (HasPointerLock()) {
    nsIDocument::UnlockPointer();
  }
  if (mState.HasState(NS_EVENT_STATE_FULLSCREEN)) {
    // The element being removed is an ancestor of the fullscreen element,
    // exit fullscreen state.
    nsContentUtils::ReportToConsole(nsIScriptError::warningFlag,
                                    NS_LITERAL_CSTRING("DOM"), OwnerDoc(),
                                    nsContentUtils::eDOM_PROPERTIES,
                                    "RemovedFullscreenElement");
    // Fully exit fullscreen.
    nsIDocument::ExitFullscreenInDocTree(OwnerDoc());
  }

  if (HasServoData()) {
    MOZ_ASSERT(document);
    MOZ_ASSERT(IsInAnonymousSubtree());
  }

  if (document) {
    ClearServoData(document);
  }

  if (aNullParent) {
    if (GetParent() && GetParent()->IsInUncomposedDoc()) {
      // Update the editable descendant count in the ancestors before we
      // lose the reference to the parent.
      int32_t editableDescendantChange = -1 * EditableInclusiveDescendantCount(this);
      if (editableDescendantChange != 0) {
        nsIContent* parent = GetParent();
        while (parent) {
          parent->ChangeEditableDescendantCount(editableDescendantChange);
          parent = parent->GetParent();
        }
      }
    }

    if (IsRootOfNativeAnonymousSubtree()) {
      nsNodeUtils::NativeAnonymousChildListChange(this, true);
    }

    if (GetParent()) {
      RefPtr<nsINode> p;
      p.swap(mParent);
    } else {
      mParent = nullptr;
    }
    SetParentIsContent(false);
  }

#ifdef DEBUG
  // If we can get access to the PresContext, then we sanity-check that
  // we're not leaving behind a pointer to ourselves as the PresContext's
  // cached provider of the viewport's scrollbar styles.
  if (document) {
    nsPresContext* presContext = document->GetPresContext();
    if (presContext) {
      MOZ_ASSERT(this !=
                 presContext->GetViewportScrollStylesOverrideElement(),
                 "Leaving behind a raw pointer to this element (as having "
                 "propagated scrollbar styles) - that's dangerous...");
    }
  }
#endif

  ClearInDocument();
  SetIsConnected(false);

  // Ensure that CSS transitions don't continue on an element at a
  // different place in the tree (even if reinserted before next
  // animation refresh).
  // We need to delete the properties while we're still in document
  // (if we were in document).
  // FIXME (Bug 522599): Need a test for this.
  if (MayHaveAnimations()) {
    DeleteProperty(nsGkAtoms::transitionsOfBeforeProperty);
    DeleteProperty(nsGkAtoms::transitionsOfAfterProperty);
    DeleteProperty(nsGkAtoms::transitionsProperty);
    DeleteProperty(nsGkAtoms::animationsOfBeforeProperty);
    DeleteProperty(nsGkAtoms::animationsOfAfterProperty);
    DeleteProperty(nsGkAtoms::animationsProperty);
    if (document) {
      if (nsPresContext* presContext = document->GetPresContext()) {
        // We have to clear all pending restyle requests for the animations on
        // this element to avoid unnecessary restyles when we re-attached this
        // element.
        presContext->EffectCompositor()->ClearRestyleRequestsFor(this);
      }
    }
  }

  // Editable descendant count only counts descendants that
  // are in the uncomposed document.
  ResetEditableDescendantCount();

  if (aNullParent || !mParent->IsInShadowTree()) {
    UnsetFlags(NODE_IS_IN_SHADOW_TREE);

    // Begin keeping track of our subtree root.
    SetSubtreeRootPointer(aNullParent ? this : mParent->SubtreeRoot());
  }

  bool clearBindingParent = true;

#ifdef MOZ_XUL
  if (nsXULElement* xulElem = nsXULElement::FromNode(this)) {;
    xulElem->SetXULBindingParent(nullptr);
    clearBindingParent = false;
  }
#endif

  if (nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots()) {
    if (clearBindingParent) {
      slots->mBindingParent = nullptr;
    }
    if (aNullParent || !mParent->IsInShadowTree()) {
      slots->mContainingShadow = nullptr;
    }
  }

  if (document) {
    if (HasFlag(NODE_MAY_BE_IN_BINDING_MNGR)) {
      // Notify XBL- & nsIAnonymousContentCreator-generated anonymous content
      // that the document is changing.
      nsContentUtils::AddScriptRunner(
        new RemoveFromBindingManagerRunnable(
          document->BindingManager(), this, document));
      nsXBLBinding* binding =
        document->BindingManager()->GetBindingWithContent(this);
      if (binding) {
        nsXBLBinding::UnbindAnonymousContent(
          document,
          binding->GetAnonymousContent(),
          /* aNullParent */ false);
      }
    }

    document->ClearBoxObjectFor(this);

     // Disconnected must be enqueued whenever a connected custom element becomes
     // disconnected.
    if (CustomElementRegistry::IsCustomElementEnabled(OwnerDoc())) {
      CustomElementData* data  = GetCustomElementData();
      if (data) {
        if (data->mState == CustomElementData::State::eCustom) {
          nsContentUtils::EnqueueLifecycleCallback(nsIDocument::eDisconnected,
                                                   this);
        } else {
          // Remove an unresolved custom element that is a candidate for upgrade
          // when a custom element is disconnected.
          nsContentUtils::UnregisterUnresolvedElement(this);
        }
      }
    }
  }

  // This has to be here, rather than in nsGenericHTMLElement::UnbindFromTree,
  //  because it has to happen after unsetting the parent pointer, but before
  //  recursively unbinding the kids.
  if (IsHTMLElement()) {
    ResetDir(this);
  }

  if (aDeep) {
    for (nsIContent* child = GetFirstChild(); child;
         child = child->GetNextSibling()) {
      // Note that we pass false for aNullParent here, since we don't want
      // the kids to forget us.  We _do_ want them to forget their binding
      // parent, though, since this only walks non-anonymous kids.
      child->UnbindFromTree(true, false);
    }
  }

  nsNodeUtils::ParentChainChanged(this);

  // Unbind children of shadow root.
  if (ShadowRoot* shadowRoot = GetShadowRoot()) {
    shadowRoot->Unbind();
  }

  MOZ_ASSERT(!HasAnyOfFlags(kAllServoDescendantBits));
  MOZ_ASSERT(!document || document->GetServoRestyleRoot() != this);
}

nsDOMCSSAttributeDeclaration*
Element::SMILOverrideStyle()
{
  Element::nsExtendedDOMSlots* slots = ExtendedDOMSlots();

  if (!slots->mSMILOverrideStyle) {
    slots->mSMILOverrideStyle = new nsDOMCSSAttributeDeclaration(this, true);
  }

  return slots->mSMILOverrideStyle;
}

DeclarationBlock*
Element::GetSMILOverrideStyleDeclaration()
{
  Element::nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
  return slots ? slots->mSMILOverrideStyleDeclaration.get() : nullptr;
}

nsresult
Element::SetSMILOverrideStyleDeclaration(DeclarationBlock* aDeclaration,
                                         bool aNotify)
{
  Element::nsExtendedDOMSlots* slots = ExtendedDOMSlots();

  slots->mSMILOverrideStyleDeclaration = aDeclaration;

  if (aNotify) {
    nsIDocument* doc = GetComposedDoc();
    // Only need to request a restyle if we're in a document.  (We might not
    // be in a document, if we're clearing animation effects on a target node
    // that's been detached since the previous animation sample.)
    if (doc) {
      nsCOMPtr<nsIPresShell> shell = doc->GetShell();
      if (shell) {
        shell->RestyleForAnimation(this, eRestyle_StyleAttribute_Animations);
      }
    }
  }

  return NS_OK;
}

bool
Element::IsLabelable() const
{
  return false;
}

bool
Element::IsInteractiveHTMLContent(bool aIgnoreTabindex) const
{
  return false;
}

DeclarationBlock*
Element::GetInlineStyleDeclaration() const
{
  if (!MayHaveStyle()) {
    return nullptr;
  }
  const nsAttrValue* attrVal = mAttrs.GetAttr(nsGkAtoms::style);

  if (attrVal && attrVal->Type() == nsAttrValue::eCSSDeclaration) {
    return attrVal->GetCSSDeclarationValue();
  }

  return nullptr;
}

const nsMappedAttributes*
Element::GetMappedAttributes() const
{
  return mAttrs.GetMapped();
}

void
Element::InlineStyleDeclarationWillChange(MutationClosureData& aData)
{
  MOZ_ASSERT_UNREACHABLE("Element::InlineStyleDeclarationWillChange");
}

nsresult
Element::SetInlineStyleDeclaration(DeclarationBlock& aDeclaration,
                                   MutationClosureData& aData)
{
  MOZ_ASSERT_UNREACHABLE("Element::SetInlineStyleDeclaration");
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP_(bool)
Element::IsAttributeMapped(const nsAtom* aAttribute) const
{
  return false;
}

nsChangeHint
Element::GetAttributeChangeHint(const nsAtom* aAttribute,
                                int32_t aModType) const
{
  return nsChangeHint(0);
}

bool
Element::FindAttributeDependence(const nsAtom* aAttribute,
                                 const MappedAttributeEntry* const aMaps[],
                                 uint32_t aMapCount)
{
  for (uint32_t mapindex = 0; mapindex < aMapCount; ++mapindex) {
    for (const MappedAttributeEntry* map = aMaps[mapindex];
         map->attribute; ++map) {
      if (aAttribute == map->attribute) {
        return true;
      }
    }
  }

  return false;
}

already_AddRefed<mozilla::dom::NodeInfo>
Element::GetExistingAttrNameFromQName(const nsAString& aStr) const
{
  const nsAttrName* name = InternalGetAttrNameFromQName(aStr);
  if (!name) {
    return nullptr;
  }

  RefPtr<mozilla::dom::NodeInfo> nodeInfo;
  if (name->IsAtom()) {
    nodeInfo = mNodeInfo->NodeInfoManager()->
      GetNodeInfo(name->Atom(), nullptr, kNameSpaceID_None, ATTRIBUTE_NODE);
  }
  else {
    nodeInfo = name->NodeInfo();
  }

  return nodeInfo.forget();
}

// static
bool
Element::ShouldBlur(nsIContent *aContent)
{
  // Determine if the current element is focused, if it is not focused
  // then we should not try to blur
  nsIDocument* document = aContent->GetComposedDoc();
  if (!document)
    return false;

  nsCOMPtr<nsPIDOMWindowOuter> window = document->GetWindow();
  if (!window)
    return false;

  nsCOMPtr<nsPIDOMWindowOuter> focusedFrame;
  nsIContent* contentToBlur =
    nsFocusManager::GetFocusedDescendant(window,
                                         nsFocusManager::eOnlyCurrentWindow,
                                         getter_AddRefs(focusedFrame));
  if (contentToBlur == aContent)
    return true;

  // if focus on this element would get redirected, then check the redirected
  // content as well when blurring.
  return (contentToBlur && nsFocusManager::GetRedirectedFocus(aContent) == contentToBlur);
}

bool
Element::IsNodeOfType(uint32_t aFlags) const
{
  return false;
}

/* static */
nsresult
Element::DispatchEvent(nsPresContext* aPresContext,
                       WidgetEvent* aEvent,
                       nsIContent* aTarget,
                       bool aFullDispatch,
                       nsEventStatus* aStatus)
{
  MOZ_ASSERT(aTarget, "Must have target");
  MOZ_ASSERT(aEvent, "Must have source event");
  MOZ_ASSERT(aStatus, "Null out param?");

  if (!aPresContext) {
    return NS_OK;
  }

  nsCOMPtr<nsIPresShell> shell = aPresContext->GetPresShell();
  if (!shell) {
    return NS_OK;
  }

  if (aFullDispatch) {
    return shell->HandleEventWithTarget(aEvent, nullptr, aTarget, aStatus);
  }

  return shell->HandleDOMEventWithTarget(aTarget, aEvent, aStatus);
}

/* static */
nsresult
Element::DispatchClickEvent(nsPresContext* aPresContext,
                            WidgetInputEvent* aSourceEvent,
                            nsIContent* aTarget,
                            bool aFullDispatch,
                            const EventFlags* aExtraEventFlags,
                            nsEventStatus* aStatus)
{
  MOZ_ASSERT(aTarget, "Must have target");
  MOZ_ASSERT(aSourceEvent, "Must have source event");
  MOZ_ASSERT(aStatus, "Null out param?");

  WidgetMouseEvent event(aSourceEvent->IsTrusted(), eMouseClick,
                         aSourceEvent->mWidget, WidgetMouseEvent::eReal);
  event.mRefPoint = aSourceEvent->mRefPoint;
  uint32_t clickCount = 1;
  float pressure = 0;
  uint32_t pointerId = 0; // Use the default value here.
  uint16_t inputSource = 0;
  WidgetMouseEvent* sourceMouseEvent = aSourceEvent->AsMouseEvent();
  if (sourceMouseEvent) {
    clickCount = sourceMouseEvent->mClickCount;
    pressure = sourceMouseEvent->pressure;
    pointerId = sourceMouseEvent->pointerId;
    inputSource = sourceMouseEvent->inputSource;
  } else if (aSourceEvent->mClass == eKeyboardEventClass) {
    event.mFlags.mIsPositionless = true;
    inputSource = MouseEvent_Binding::MOZ_SOURCE_KEYBOARD;
  }
  event.pressure = pressure;
  event.mClickCount = clickCount;
  event.pointerId = pointerId;
  event.inputSource = inputSource;
  event.mModifiers = aSourceEvent->mModifiers;
  if (aExtraEventFlags) {
    // Be careful not to overwrite existing flags!
    event.mFlags.Union(*aExtraEventFlags);
  }

  return DispatchEvent(aPresContext, &event, aTarget, aFullDispatch, aStatus);
}

nsIFrame*
Element::GetPrimaryFrame(FlushType aType)
{
  nsIDocument* doc = GetComposedDoc();
  if (!doc) {
    return nullptr;
  }

  // Cause a flush, so we get up-to-date frame
  // information
  if (aType != FlushType::None) {
    doc->FlushPendingNotifications(aType);
  }

  return GetPrimaryFrame();
}

//----------------------------------------------------------------------
nsresult
Element::LeaveLink(nsPresContext* aPresContext)
{
  nsILinkHandler *handler = aPresContext->GetLinkHandler();
  if (!handler) {
    return NS_OK;
  }

  return handler->OnLeaveLink();
}

nsresult
Element::SetEventHandler(nsAtom* aEventName,
                         const nsAString& aValue,
                         bool aDefer)
{
  nsIDocument *ownerDoc = OwnerDoc();
  if (ownerDoc->IsLoadedAsData()) {
    // Make this a no-op rather than throwing an error to avoid
    // the error causing problems setting the attribute.
    return NS_OK;
  }

  MOZ_ASSERT(aEventName, "Must have event name!");
  bool defer = true;
  EventListenerManager* manager =
    GetEventListenerManagerForAttr(aEventName, &defer);
  if (!manager) {
    return NS_OK;
  }

  defer = defer && aDefer; // only defer if everyone agrees...
  manager->SetEventHandler(aEventName, aValue,
                           defer, !nsContentUtils::IsChromeDoc(ownerDoc),
                           this);
  return NS_OK;
}


//----------------------------------------------------------------------

const nsAttrName*
Element::InternalGetAttrNameFromQName(const nsAString& aStr,
                                      nsAutoString* aNameToUse) const
{
  MOZ_ASSERT(!aNameToUse || aNameToUse->IsEmpty());
  const nsAttrName* val = nullptr;
  if (IsHTMLElement() && IsInHTMLDocument()) {
    nsAutoString lower;
    nsAutoString& outStr = aNameToUse ? *aNameToUse : lower;
    nsContentUtils::ASCIIToLower(aStr, outStr);
    val = mAttrs.GetExistingAttrNameFromQName(outStr);
    if (val) {
      outStr.Truncate();
    }
  } else {
    val = mAttrs.GetExistingAttrNameFromQName(aStr);
    if (!val && aNameToUse) {
      *aNameToUse = aStr;
    }
  }

  return val;
}

bool
Element::MaybeCheckSameAttrVal(int32_t aNamespaceID,
                               nsAtom* aName,
                               nsAtom* aPrefix,
                               const nsAttrValueOrString& aValue,
                               bool aNotify,
                               nsAttrValue& aOldValue,
                               uint8_t* aModType,
                               bool* aHasListeners,
                               bool* aOldValueSet)
{
  bool modification = false;
  *aHasListeners = aNotify &&
    nsContentUtils::HasMutationListeners(this,
                                         NS_EVENT_BITS_MUTATION_ATTRMODIFIED,
                                         this);
  *aOldValueSet = false;

  // If we have no listeners and aNotify is false, we are almost certainly
  // coming from the content sink and will almost certainly have no previous
  // value.  Even if we do, setting the value is cheap when we have no
  // listeners and don't plan to notify.  The check for aNotify here is an
  // optimization, the check for *aHasListeners is a correctness issue.
  if (*aHasListeners || aNotify) {
    BorrowedAttrInfo info(GetAttrInfo(aNamespaceID, aName));
    if (info.mValue) {
      // Check whether the old value is the same as the new one.  Note that we
      // only need to actually _get_ the old value if we have listeners or
      // if the element is a custom element (because it may have an
      // attribute changed callback).
      if (*aHasListeners || GetCustomElementData()) {
        // Need to store the old value.
        //
        // If the current attribute value contains a pointer to some other data
        // structure that gets updated in the process of setting the attribute
        // we'll no longer have the old value of the attribute. Therefore, we
        // should serialize the attribute value now to keep a snapshot.
        //
        // We have to serialize the value anyway in order to create the
        // mutation event so there's no cost in doing it now.
        aOldValue.SetToSerialized(*info.mValue);
        *aOldValueSet = true;
      }
      bool valueMatches = aValue.EqualsAsStrings(*info.mValue);
      if (valueMatches && aPrefix == info.mName->GetPrefix()) {
        return true;
      }
      modification = true;
    }
  }
  *aModType = modification ?
    static_cast<uint8_t>(MutationEvent_Binding::MODIFICATION) :
    static_cast<uint8_t>(MutationEvent_Binding::ADDITION);
  return false;
}

bool
Element::OnlyNotifySameValueSet(int32_t aNamespaceID, nsAtom* aName,
                                nsAtom* aPrefix,
                                const nsAttrValueOrString& aValue,
                                bool aNotify, nsAttrValue& aOldValue,
                                uint8_t* aModType, bool* aHasListeners,
                                bool* aOldValueSet)
{
  if (!MaybeCheckSameAttrVal(aNamespaceID, aName, aPrefix, aValue, aNotify,
                             aOldValue, aModType, aHasListeners,
                             aOldValueSet)) {
    return false;
  }

  nsAutoScriptBlocker scriptBlocker;
  nsNodeUtils::AttributeSetToCurrentValue(this, aNamespaceID, aName);
  return true;
}

nsresult
Element::SetSingleClassFromParser(nsAtom* aSingleClassName)
{
  // Keep this in sync with SetAttr and SetParsedAttr below.

  nsAttrValue value(aSingleClassName);

  nsIDocument* document = GetComposedDoc();
  mozAutoDocUpdate updateBatch(document, false);

  // In principle, BeforeSetAttr should be called here if a node type
  // existed that wanted to do something special for class, but there
  // is no such node type, so calling SetMayHaveClass() directly.
  SetMayHaveClass();

  return SetAttrAndNotify(kNameSpaceID_None,
                          nsGkAtoms::_class,
                          nullptr, // prefix
                          nullptr, // old value
                          value,
                          nullptr,
                          static_cast<uint8_t>(MutationEvent_Binding::ADDITION),
                          false, // hasListeners
                          false, // notify
                          kCallAfterSetAttr,
                          document,
                          updateBatch);
}

nsresult
Element::SetAttr(int32_t aNamespaceID, nsAtom* aName,
                 nsAtom* aPrefix, const nsAString& aValue,
                 nsIPrincipal* aSubjectPrincipal,
                 bool aNotify)
{
  // Keep this in sync with SetParsedAttr below and SetSingleClassFromParser
  // above.

  NS_ENSURE_ARG_POINTER(aName);
  NS_ASSERTION(aNamespaceID != kNameSpaceID_Unknown,
               "Don't call SetAttr with unknown namespace");

  uint8_t modType;
  bool hasListeners;
  // We don't want to spend time preparsing class attributes if the value is not
  // changing, so just init our nsAttrValueOrString with aValue for the
  // OnlyNotifySameValueSet call.
  nsAttrValueOrString value(aValue);
  nsAttrValue oldValue;
  bool oldValueSet;

  if (OnlyNotifySameValueSet(aNamespaceID, aName, aPrefix, value, aNotify,
                             oldValue, &modType, &hasListeners, &oldValueSet)) {
    return OnAttrSetButNotChanged(aNamespaceID, aName, value, aNotify);
  }

  nsAttrValue attrValue;
  nsAttrValue* preparsedAttrValue;
  if (aNamespaceID == kNameSpaceID_None && aName == nsGkAtoms::_class) {
    attrValue.ParseAtomArray(aValue);
    value.ResetToAttrValue(attrValue);
    preparsedAttrValue = &attrValue;
  } else {
    preparsedAttrValue = nullptr;
  }

  if (aNotify) {
    nsNodeUtils::AttributeWillChange(this, aNamespaceID, aName, modType,
                                     preparsedAttrValue);
  }

  // Hold a script blocker while calling ParseAttribute since that can call
  // out to id-observers
  nsIDocument* document = GetComposedDoc();
  mozAutoDocUpdate updateBatch(document, aNotify);

  nsresult rv = BeforeSetAttr(aNamespaceID, aName, &value, aNotify);
  NS_ENSURE_SUCCESS(rv, rv);

  if (!preparsedAttrValue &&
      !ParseAttribute(aNamespaceID, aName, aValue, aSubjectPrincipal,
                      attrValue)) {
    attrValue.SetTo(aValue);
  }

  PreIdMaybeChange(aNamespaceID, aName, &value);

  return SetAttrAndNotify(aNamespaceID, aName, aPrefix,
                          oldValueSet ? &oldValue : nullptr,
                          attrValue, aSubjectPrincipal, modType,
                          hasListeners, aNotify,
                          kCallAfterSetAttr, document, updateBatch);
}

nsresult
Element::SetParsedAttr(int32_t aNamespaceID, nsAtom* aName,
                       nsAtom* aPrefix, nsAttrValue& aParsedValue,
                       bool aNotify)
{
  // Keep this in sync with SetAttr and SetSingleClassFromParser above

  NS_ENSURE_ARG_POINTER(aName);
  NS_ASSERTION(aNamespaceID != kNameSpaceID_Unknown,
               "Don't call SetAttr with unknown namespace");

  uint8_t modType;
  bool hasListeners;
  nsAttrValueOrString value(aParsedValue);
  nsAttrValue oldValue;
  bool oldValueSet;

  if (OnlyNotifySameValueSet(aNamespaceID, aName, aPrefix, value, aNotify,
                             oldValue, &modType, &hasListeners, &oldValueSet)) {
    return OnAttrSetButNotChanged(aNamespaceID, aName, value, aNotify);
  }

  if (aNotify) {
    nsNodeUtils::AttributeWillChange(this, aNamespaceID, aName, modType,
                                     &aParsedValue);
  }

  nsresult rv = BeforeSetAttr(aNamespaceID, aName, &value, aNotify);
  NS_ENSURE_SUCCESS(rv, rv);

  PreIdMaybeChange(aNamespaceID, aName, &value);

  nsIDocument* document = GetComposedDoc();
  mozAutoDocUpdate updateBatch(document, aNotify);
  return SetAttrAndNotify(aNamespaceID, aName, aPrefix,
                          oldValueSet ? &oldValue : nullptr,
                          aParsedValue, nullptr, modType, hasListeners, aNotify,
                          kCallAfterSetAttr, document, updateBatch);
}

nsresult
Element::SetAttrAndNotify(int32_t aNamespaceID,
                          nsAtom* aName,
                          nsAtom* aPrefix,
                          const nsAttrValue* aOldValue,
                          nsAttrValue& aParsedValue,
                          nsIPrincipal* aSubjectPrincipal,
                          uint8_t aModType,
                          bool aFireMutation,
                          bool aNotify,
                          bool aCallAfterSetAttr,
                          nsIDocument* aComposedDocument,
                          const mozAutoDocUpdate&)
{
  nsresult rv;
  nsMutationGuard::DidMutate();

  // Copy aParsedValue for later use since it will be lost when we call
  // SetAndSwapMappedAttr below
  nsAttrValue valueForAfterSetAttr;
  if (aCallAfterSetAttr || GetCustomElementData()) {
    valueForAfterSetAttr.SetTo(aParsedValue);
  }

  bool hadValidDir = false;
  bool hadDirAuto = false;
  bool oldValueSet;

  if (aNamespaceID == kNameSpaceID_None) {
    if (aName == nsGkAtoms::dir) {
      hadValidDir = HasValidDir() || IsHTMLElement(nsGkAtoms::bdi);
      hadDirAuto = HasDirAuto(); // already takes bdi into account
    }

    // XXXbz Perhaps we should push up the attribute mapping function
    // stuff to Element?
    if (!IsAttributeMapped(aName) ||
        !SetAndSwapMappedAttribute(aName, aParsedValue, &oldValueSet, &rv)) {
      rv = mAttrs.SetAndSwapAttr(aName, aParsedValue, &oldValueSet);
    }
  }
  else {
    RefPtr<mozilla::dom::NodeInfo> ni;
    ni = mNodeInfo->NodeInfoManager()->GetNodeInfo(aName, aPrefix,
                                                   aNamespaceID,
                                                   ATTRIBUTE_NODE);

    rv = mAttrs.SetAndSwapAttr(ni, aParsedValue, &oldValueSet);
  }
  NS_ENSURE_SUCCESS(rv, rv);

  PostIdMaybeChange(aNamespaceID, aName, &valueForAfterSetAttr);

  // If the old value owns its own data, we know it is OK to keep using it.
  // oldValue will be null if there was no previously set value
  const nsAttrValue* oldValue;
  if (aParsedValue.StoresOwnData()) {
    if (oldValueSet) {
      oldValue = &aParsedValue;
    } else {
      oldValue = nullptr;
    }
  } else {
    // No need to conditionally assign null here. If there was no previously
    // set value for the attribute, aOldValue will already be null.
    oldValue = aOldValue;
  }

  if (aComposedDocument) {
    RefPtr<nsXBLBinding> binding = GetXBLBinding();
    if (binding) {
      binding->AttributeChanged(aName, aNamespaceID, false, aNotify);
    }
  }

  if (CustomElementRegistry::IsCustomElementEnabled(OwnerDoc())) {
    CustomElementDefinition* definition = GetCustomElementDefinition();
    // Only custom element which is in `custom` state could get the
    // CustomElementDefinition.
    if (definition && definition->IsInObservedAttributeList(aName)) {
      RefPtr<nsAtom> oldValueAtom;
      if (oldValue) {
        oldValueAtom = oldValue->GetAsAtom();
      } else {
        // If there is no old value, get the value of the uninitialized
        // attribute that was swapped with aParsedValue.
        oldValueAtom = aParsedValue.GetAsAtom();
      }
      RefPtr<nsAtom> newValueAtom = valueForAfterSetAttr.GetAsAtom();
      nsAutoString ns;
      nsContentUtils::NameSpaceManager()->GetNameSpaceURI(aNamespaceID, ns);

      LifecycleCallbackArgs args = {
        nsDependentAtomString(aName),
        aModType == MutationEvent_Binding::ADDITION ?
          VoidString() : nsDependentAtomString(oldValueAtom),
        nsDependentAtomString(newValueAtom),
        (ns.IsEmpty() ? VoidString() : ns)
      };

      nsContentUtils::EnqueueLifecycleCallback(nsIDocument::eAttributeChanged,
        this, &args, nullptr, definition);
    }
  }

  if (aCallAfterSetAttr) {
    rv = AfterSetAttr(aNamespaceID, aName, &valueForAfterSetAttr, oldValue,
                      aSubjectPrincipal, aNotify);
    NS_ENSURE_SUCCESS(rv, rv);

    if (aNamespaceID == kNameSpaceID_None && aName == nsGkAtoms::dir) {
      OnSetDirAttr(this, &valueForAfterSetAttr,
                   hadValidDir, hadDirAuto, aNotify);
    }
  }

  UpdateState(aNotify);

  if (aNotify) {
    // Don't pass aOldValue to AttributeChanged since it may not be reliable.
    // Callers only compute aOldValue under certain conditions which may not
    // be triggered by all nsIMutationObservers.
    nsNodeUtils::AttributeChanged(this, aNamespaceID, aName, aModType,
        aParsedValue.StoresOwnData() ? &aParsedValue : nullptr);
  }

  if (aFireMutation) {
    InternalMutationEvent mutation(true, eLegacyAttrModified);

    nsAutoString ns;
    nsContentUtils::NameSpaceManager()->GetNameSpaceURI(aNamespaceID, ns);
    Attr* attrNode =
      GetAttributeNodeNSInternal(ns, nsDependentAtomString(aName));
    mutation.mRelatedNode = attrNode;

    mutation.mAttrName = aName;
    nsAutoString newValue;
    GetAttr(aNamespaceID, aName, newValue);
    if (!newValue.IsEmpty()) {
      mutation.mNewAttrValue = NS_Atomize(newValue);
    }
    if (oldValue && !oldValue->IsEmptyString()) {
      mutation.mPrevAttrValue = oldValue->GetAsAtom();
    }
    mutation.mAttrChange = aModType;

    mozAutoSubtreeModified subtree(OwnerDoc(), this);
    (new AsyncEventDispatcher(this, mutation))->RunDOMEventWhenSafe();
  }

  return NS_OK;
}

bool
Element::ParseAttribute(int32_t aNamespaceID,
                        nsAtom* aAttribute,
                        const nsAString& aValue,
                        nsIPrincipal* aMaybeScriptedPrincipal,
                        nsAttrValue& aResult)
{
  if (aAttribute == nsGkAtoms::lang) {
    aResult.ParseAtom(aValue);
    return true;
  }

  if (aNamespaceID == kNameSpaceID_None) {
    MOZ_ASSERT(aAttribute != nsGkAtoms::_class,
               "The class attribute should be preparsed and therefore should "
               "never be passed to Element::ParseAttribute");
    if (aAttribute == nsGkAtoms::id) {
      // Store id as an atom.  id="" means that the element has no id,
      // not that it has an emptystring as the id.
      if (aValue.IsEmpty()) {
        return false;
      }
      aResult.ParseAtom(aValue);
      return true;
    }
  }

  return false;
}

bool
Element::SetAndSwapMappedAttribute(nsAtom* aName,
                                   nsAttrValue& aValue,
                                   bool* aValueWasSet,
                                   nsresult* aRetval)
{
  *aRetval = NS_OK;
  return false;
}

nsresult
Element::BeforeSetAttr(int32_t aNamespaceID, nsAtom* aName,
                       const nsAttrValueOrString* aValue, bool aNotify)
{
  if (aNamespaceID == kNameSpaceID_None) {
    if (aName == nsGkAtoms::_class) {
      if (aValue) {
        // Note: This flag is asymmetrical. It is never unset and isn't exact.
        // If it is ever made to be exact, we probably need to handle this
        // similarly to how ids are handled in PreIdMaybeChange and
        // PostIdMaybeChange.
        // Note that SetSingleClassFromParser inlines BeforeSetAttr and
        // calls SetMayHaveClass directly. Making a subclass take action
        // on the class attribute in a BeforeSetAttr override would
        // require revising SetSingleClassFromParser.
        SetMayHaveClass();
      }
    }
  }

  return NS_OK;
}

void
Element::PreIdMaybeChange(int32_t aNamespaceID, nsAtom* aName,
                          const nsAttrValueOrString* aValue)
{
  if (aNamespaceID != kNameSpaceID_None || aName != nsGkAtoms::id) {
    return;
  }
  RemoveFromIdTable();
}

void
Element::PostIdMaybeChange(int32_t aNamespaceID, nsAtom* aName,
                           const nsAttrValue* aValue)
{
  if (aNamespaceID != kNameSpaceID_None || aName != nsGkAtoms::id) {
    return;
  }

  // id="" means that the element has no id, not that it has an empty
  // string as the id.
  if (aValue && !aValue->IsEmptyString()) {
    SetHasID();
    AddToIdTable(aValue->GetAtomValue());
  } else {
    ClearHasID();
  }
}

nsresult
Element::OnAttrSetButNotChanged(int32_t aNamespaceID, nsAtom* aName,
                                const nsAttrValueOrString& aValue,
                                bool aNotify)
{
  if (CustomElementRegistry::IsCustomElementEnabled(OwnerDoc())) {
    // Only custom element which is in `custom` state could get the
    // CustomElementDefinition.
    CustomElementDefinition* definition = GetCustomElementDefinition();
    if (definition && definition->IsInObservedAttributeList(aName)) {
      nsAutoString ns;
      nsContentUtils::NameSpaceManager()->GetNameSpaceURI(aNamespaceID, ns);

      nsAutoString value(aValue.String());
      LifecycleCallbackArgs args = {
        nsDependentAtomString(aName),
        value,
        value,
        (ns.IsEmpty() ? VoidString() : ns)
      };

      nsContentUtils::EnqueueLifecycleCallback(nsIDocument::eAttributeChanged,
        this, &args, nullptr, definition);
    }
  }

  return NS_OK;
}

EventListenerManager*
Element::GetEventListenerManagerForAttr(nsAtom* aAttrName,
                                        bool* aDefer)
{
  *aDefer = true;
  return GetOrCreateListenerManager();
}

bool
Element::GetAttr(int32_t aNameSpaceID, nsAtom* aName,
                 nsAString& aResult) const
{
  DOMString str;
  bool haveAttr = GetAttr(aNameSpaceID, aName, str);
  str.ToString(aResult);
  return haveAttr;
}

int32_t
Element::FindAttrValueIn(int32_t aNameSpaceID,
                         nsAtom* aName,
                         AttrValuesArray* aValues,
                         nsCaseTreatment aCaseSensitive) const
{
  NS_ASSERTION(aName, "Must have attr name");
  NS_ASSERTION(aNameSpaceID != kNameSpaceID_Unknown, "Must have namespace");
  NS_ASSERTION(aValues, "Null value array");

  const nsAttrValue* val = mAttrs.GetAttr(aName, aNameSpaceID);
  if (val) {
    for (int32_t i = 0; aValues[i]; ++i) {
      if (val->Equals(aValues[i], aCaseSensitive)) {
        return i;
      }
    }
    return ATTR_VALUE_NO_MATCH;
  }
  return ATTR_MISSING;
}

nsresult
Element::UnsetAttr(int32_t aNameSpaceID, nsAtom* aName,
                   bool aNotify)
{
  NS_ASSERTION(nullptr != aName, "must have attribute name");

  int32_t index = mAttrs.IndexOfAttr(aName, aNameSpaceID);
  if (index < 0) {
    return NS_OK;
  }

  nsIDocument *document = GetComposedDoc();
  mozAutoDocUpdate updateBatch(document, aNotify);

  if (aNotify) {
    nsNodeUtils::AttributeWillChange(this, aNameSpaceID, aName,
                                     MutationEvent_Binding::REMOVAL,
                                     nullptr);
  }

  nsresult rv = BeforeSetAttr(aNameSpaceID, aName, nullptr, aNotify);
  NS_ENSURE_SUCCESS(rv, rv);

  bool hasMutationListeners = aNotify &&
    nsContentUtils::HasMutationListeners(this,
                                         NS_EVENT_BITS_MUTATION_ATTRMODIFIED,
                                         this);

  PreIdMaybeChange(aNameSpaceID, aName, nullptr);

  // Grab the attr node if needed before we remove it from the attr map
  RefPtr<Attr> attrNode;
  if (hasMutationListeners) {
    nsAutoString ns;
    nsContentUtils::NameSpaceManager()->GetNameSpaceURI(aNameSpaceID, ns);
    attrNode = GetAttributeNodeNSInternal(ns, nsDependentAtomString(aName));
  }

  // Clear the attribute out from attribute map.
  nsDOMSlots *slots = GetExistingDOMSlots();
  if (slots && slots->mAttributeMap) {
    slots->mAttributeMap->DropAttribute(aNameSpaceID, aName);
  }

  // The id-handling code, and in the future possibly other code, need to
  // react to unexpected attribute changes.
  nsMutationGuard::DidMutate();

  bool hadValidDir = false;
  bool hadDirAuto = false;

  if (aNameSpaceID == kNameSpaceID_None && aName == nsGkAtoms::dir) {
    hadValidDir = HasValidDir() || IsHTMLElement(nsGkAtoms::bdi);
    hadDirAuto = HasDirAuto(); // already takes bdi into account
  }

  nsAttrValue oldValue;
  rv = mAttrs.RemoveAttrAt(index, oldValue);
  NS_ENSURE_SUCCESS(rv, rv);

  PostIdMaybeChange(aNameSpaceID, aName, nullptr);

  if (document) {
    RefPtr<nsXBLBinding> binding = GetXBLBinding();
    if (binding) {
      binding->AttributeChanged(aName, aNameSpaceID, true, aNotify);
    }
  }

  if (CustomElementRegistry::IsCustomElementEnabled(OwnerDoc())) {
    CustomElementDefinition* definition = GetCustomElementDefinition();
    // Only custom element which is in `custom` state could get the
    // CustomElementDefinition.
    if (definition && definition->IsInObservedAttributeList(aName)) {
      nsAutoString ns;
      nsContentUtils::NameSpaceManager()->GetNameSpaceURI(aNameSpaceID, ns);

      RefPtr<nsAtom> oldValueAtom = oldValue.GetAsAtom();
      LifecycleCallbackArgs args = {
        nsDependentAtomString(aName),
        nsDependentAtomString(oldValueAtom),
        VoidString(),
        (ns.IsEmpty() ? VoidString() : ns)
      };

      nsContentUtils::EnqueueLifecycleCallback(nsIDocument::eAttributeChanged,
        this, &args, nullptr, definition);
    }
  }

  rv = AfterSetAttr(aNameSpaceID, aName, nullptr, &oldValue, nullptr, aNotify);
  NS_ENSURE_SUCCESS(rv, rv);

  UpdateState(aNotify);

  if (aNotify) {
    // We can always pass oldValue here since there is no new value which could
    // have corrupted it.
    nsNodeUtils::AttributeChanged(this, aNameSpaceID, aName,
                                  MutationEvent_Binding::REMOVAL, &oldValue);
  }

  if (aNameSpaceID == kNameSpaceID_None && aName == nsGkAtoms::dir) {
    OnSetDirAttr(this, nullptr, hadValidDir, hadDirAuto, aNotify);
  }

  if (hasMutationListeners) {
    InternalMutationEvent mutation(true, eLegacyAttrModified);

    mutation.mRelatedNode = attrNode;
    mutation.mAttrName = aName;

    nsAutoString value;
    oldValue.ToString(value);
    if (!value.IsEmpty())
      mutation.mPrevAttrValue = NS_Atomize(value);
    mutation.mAttrChange = MutationEvent_Binding::REMOVAL;

    mozAutoSubtreeModified subtree(OwnerDoc(), this);
    (new AsyncEventDispatcher(this, mutation))->RunDOMEventWhenSafe();
  }

  return NS_OK;
}

void
Element::DescribeAttribute(uint32_t index, nsAString& aOutDescription) const
{
  // name
  mAttrs.AttrNameAt(index)->GetQualifiedName(aOutDescription);

  // value
  aOutDescription.AppendLiteral("=\"");
  nsAutoString value;
  mAttrs.AttrAt(index)->ToString(value);
  for (uint32_t i = value.Length(); i > 0; --i) {
    if (value[i - 1] == char16_t('"'))
      value.Insert(char16_t('\\'), i - 1);
  }
  aOutDescription.Append(value);
  aOutDescription.Append('"');
}

#ifdef DEBUG
void
Element::ListAttributes(FILE* out) const
{
  uint32_t index, count = mAttrs.AttrCount();
  for (index = 0; index < count; index++) {
    nsAutoString attributeDescription;
    DescribeAttribute(index, attributeDescription);

    fputs(" ", out);
    fputs(NS_LossyConvertUTF16toASCII(attributeDescription).get(), out);
  }
}

void
Element::List(FILE* out, int32_t aIndent,
              const nsCString& aPrefix) const
{
  int32_t indent;
  for (indent = aIndent; --indent >= 0; ) fputs("  ", out);

  fputs(aPrefix.get(), out);

  fputs(NS_LossyConvertUTF16toASCII(mNodeInfo->QualifiedName()).get(), out);

  fprintf(out, "@%p", (void *)this);

  ListAttributes(out);

  fprintf(out, " state=[%llx]",
          static_cast<unsigned long long>(State().GetInternalValue()));
  fprintf(out, " flags=[%08x]", static_cast<unsigned int>(GetFlags()));
  if (IsCommonAncestorForRangeInSelection()) {
    const LinkedList<nsRange>* ranges = GetExistingCommonAncestorRanges();
    int32_t count = 0;
    if (ranges) {
      // Can't use range-based iteration on a const LinkedList, unfortunately.
      for (const nsRange* r = ranges->getFirst(); r; r = r->getNext()) {
        ++count;
      }
    }
    fprintf(out, " ranges:%d", count);
  }
  fprintf(out, " primaryframe=%p", static_cast<void*>(GetPrimaryFrame()));
  fprintf(out, " refcount=%" PRIuPTR "<", mRefCnt.get());

  nsIContent* child = GetFirstChild();
  if (child) {
    fputs("\n", out);

    for (; child; child = child->GetNextSibling()) {
      child->List(out, aIndent + 1);
    }

    for (indent = aIndent; --indent >= 0; ) fputs("  ", out);
  }

  fputs(">\n", out);

  Element* nonConstThis = const_cast<Element*>(this);

  // XXX sXBL/XBL2 issue! Owner or current document?
  nsIDocument *document = OwnerDoc();

  // Note: not listing nsIAnonymousContentCreator-created content...

  nsBindingManager* bindingManager = document->BindingManager();
  nsINodeList* anonymousChildren =
    bindingManager->GetAnonymousNodesFor(nonConstThis);

  if (anonymousChildren) {
    uint32_t length = anonymousChildren->Length();

    for (indent = aIndent; --indent >= 0; ) fputs("  ", out);
    fputs("anonymous-children<\n", out);

    for (uint32_t i = 0; i < length; ++i) {
      nsIContent* child = anonymousChildren->Item(i);
      child->List(out, aIndent + 1);
    }

    for (indent = aIndent; --indent >= 0; ) fputs("  ", out);
    fputs(">\n", out);

    bool outHeader = false;
    ExplicitChildIterator iter(nonConstThis);
    for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
      if (!outHeader) {
        outHeader = true;

        for (indent = aIndent; --indent >= 0; ) fputs("  ", out);
        fputs("content-list<\n", out);
      }

      child->List(out, aIndent + 1);
    }

    if (outHeader) {
      for (indent = aIndent; --indent >= 0; ) fputs("  ", out);
      fputs(">\n", out);
    }
  }
}

void
Element::DumpContent(FILE* out, int32_t aIndent,
                     bool aDumpAll) const
{
  int32_t indent;
  for (indent = aIndent; --indent >= 0; ) fputs("  ", out);

  const nsString& buf = mNodeInfo->QualifiedName();
  fputs("<", out);
  fputs(NS_LossyConvertUTF16toASCII(buf).get(), out);

  if(aDumpAll) ListAttributes(out);

  fputs(">", out);

  if(aIndent) fputs("\n", out);

  for (nsIContent* child = GetFirstChild();
       child;
       child = child->GetNextSibling()) {
    int32_t indent = aIndent ? aIndent + 1 : 0;
    child->DumpContent(out, indent, aDumpAll);
  }
  for (indent = aIndent; --indent >= 0; ) fputs("  ", out);
  fputs("</", out);
  fputs(NS_LossyConvertUTF16toASCII(buf).get(), out);
  fputs(">", out);

  if(aIndent) fputs("\n", out);
}
#endif

void
Element::Describe(nsAString& aOutDescription) const
{
  aOutDescription.Append(mNodeInfo->QualifiedName());
  aOutDescription.AppendPrintf("@%p", (void *)this);

  uint32_t index, count = mAttrs.AttrCount();
  for (index = 0; index < count; index++) {
    aOutDescription.Append(' ');
    nsAutoString attributeDescription;
    DescribeAttribute(index, attributeDescription);
    aOutDescription.Append(attributeDescription);
  }
}

bool
Element::CheckHandleEventForLinksPrecondition(EventChainVisitor& aVisitor,
                                              nsIURI** aURI) const
{
  if (aVisitor.mEventStatus == nsEventStatus_eConsumeNoDefault ||
      (!aVisitor.mEvent->IsTrusted() &&
       (aVisitor.mEvent->mMessage != eMouseClick) &&
       (aVisitor.mEvent->mMessage != eKeyPress) &&
       (aVisitor.mEvent->mMessage != eLegacyDOMActivate)) ||
      !aVisitor.mPresContext ||
      aVisitor.mEvent->mFlags.mMultipleActionsPrevented) {
    return false;
  }

  // Make sure we actually are a link
  return IsLink(aURI);
}

void
Element::GetEventTargetParentForLinks(EventChainPreVisitor& aVisitor)
{
  // Optimisation: return early if this event doesn't interest us.
  // IMPORTANT: this switch and the switch below it must be kept in sync!
  switch (aVisitor.mEvent->mMessage) {
  case eMouseOver:
  case eFocus:
  case eMouseOut:
  case eBlur:
    break;
  default:
    return;
  }

  // Make sure we meet the preconditions before continuing
  nsCOMPtr<nsIURI> absURI;
  if (!CheckHandleEventForLinksPrecondition(aVisitor, getter_AddRefs(absURI))) {
    return;
  }

  // We do the status bar updates in GetEventTargetParent so that the status bar
  // gets updated even if the event is consumed before we have a chance to set
  // it.
  switch (aVisitor.mEvent->mMessage) {
  // Set the status bar similarly for mouseover and focus
  case eMouseOver:
    aVisitor.mEventStatus = nsEventStatus_eConsumeNoDefault;
    MOZ_FALLTHROUGH;
  case eFocus: {
    InternalFocusEvent* focusEvent = aVisitor.mEvent->AsFocusEvent();
    if (!focusEvent || !focusEvent->mIsRefocus) {
      nsAutoString target;
      GetLinkTarget(target);
      nsContentUtils::TriggerLink(this, aVisitor.mPresContext, absURI, target,
                                  /* click */ false, /* isTrusted */ true);
      // Make sure any ancestor links don't also TriggerLink
      aVisitor.mEvent->mFlags.mMultipleActionsPrevented = true;
    }
    break;
  }
  case eMouseOut:
    aVisitor.mEventStatus = nsEventStatus_eConsumeNoDefault;
    MOZ_FALLTHROUGH;
  case eBlur:
    {
      nsresult rv = LeaveLink(aVisitor.mPresContext);
      if (NS_SUCCEEDED(rv)) {
        aVisitor.mEvent->mFlags.mMultipleActionsPrevented = true;
      }
      break;
    }

  default:
    // switch not in sync with the optimization switch earlier in this function
    MOZ_ASSERT_UNREACHABLE("switch statements not in sync");
  }
}

nsresult
Element::PostHandleEventForLinks(EventChainPostVisitor& aVisitor)
{
  // Optimisation: return early if this event doesn't interest us.
  // IMPORTANT: this switch and the switch below it must be kept in sync!
  switch (aVisitor.mEvent->mMessage) {
  case eMouseDown:
  case eMouseClick:
  case eLegacyDOMActivate:
  case eKeyPress:
    break;
  default:
    return NS_OK;
  }

  // Make sure we meet the preconditions before continuing
  nsCOMPtr<nsIURI> absURI;
  if (!CheckHandleEventForLinksPrecondition(aVisitor, getter_AddRefs(absURI))) {
    return NS_OK;
  }

  nsresult rv = NS_OK;

  switch (aVisitor.mEvent->mMessage) {
  case eMouseDown:
    {
      if (aVisitor.mEvent->AsMouseEvent()->button ==
            WidgetMouseEvent::eLeftButton) {
        // don't make the link grab the focus if there is no link handler
        nsILinkHandler *handler = aVisitor.mPresContext->GetLinkHandler();
        nsIDocument *document = GetComposedDoc();
        if (handler && document) {
          nsIFocusManager* fm = nsFocusManager::GetFocusManager();
          if (fm) {
            aVisitor.mEvent->mFlags.mMultipleActionsPrevented = true;
            RefPtr<Element> kungFuDeathGrip(this);
            fm->SetFocus(kungFuDeathGrip, nsIFocusManager::FLAG_BYMOUSE |
                                          nsIFocusManager::FLAG_NOSCROLL);
          }

          EventStateManager::SetActiveManager(
            aVisitor.mPresContext->EventStateManager(), this);

          // OK, we're pretty sure we're going to load, so warm up a speculative
          // connection to be sure we have one ready when we open the channel.
          nsCOMPtr<nsISpeculativeConnect> sc =
            do_QueryInterface(nsContentUtils::GetIOService());
          nsCOMPtr<nsIInterfaceRequestor> ir = do_QueryInterface(handler);
          sc->SpeculativeConnect2(absURI, NodePrincipal(), ir);
        }
      }
    }
    break;

  case eMouseClick: {
    WidgetMouseEvent* mouseEvent = aVisitor.mEvent->AsMouseEvent();
    if (mouseEvent->IsLeftClickEvent()) {
      if (mouseEvent->IsControl() || mouseEvent->IsMeta() ||
          mouseEvent->IsAlt() ||mouseEvent->IsShift()) {
        break;
      }

      // The default action is simply to dispatch DOMActivate
      nsCOMPtr<nsIPresShell> shell = aVisitor.mPresContext->GetPresShell();
      if (shell) {
        // single-click
        nsEventStatus status = nsEventStatus_eIgnore;
        // DOMActive event should be trusted since the activation is actually
        // occurred even if the cause is an untrusted click event.
        InternalUIEvent actEvent(true, eLegacyDOMActivate, mouseEvent);
        actEvent.mDetail = 1;

        rv = shell->HandleDOMEventWithTarget(this, &actEvent, &status);
        if (NS_SUCCEEDED(rv)) {
          aVisitor.mEventStatus = nsEventStatus_eConsumeNoDefault;
        }
      }
    }
    break;
  }
  case eLegacyDOMActivate:
    {
      if (aVisitor.mEvent->mOriginalTarget == this) {
        nsAutoString target;
        GetLinkTarget(target);
        const InternalUIEvent* activeEvent = aVisitor.mEvent->AsUIEvent();
        MOZ_ASSERT(activeEvent);
        nsContentUtils::TriggerLink(this, aVisitor.mPresContext, absURI, target,
                                    /* click */ true, activeEvent->IsTrustable());
        aVisitor.mEventStatus = nsEventStatus_eConsumeNoDefault;
      }
    }
    break;

  case eKeyPress:
    {
      WidgetKeyboardEvent* keyEvent = aVisitor.mEvent->AsKeyboardEvent();
      if (keyEvent && keyEvent->mKeyCode == NS_VK_RETURN) {
        nsEventStatus status = nsEventStatus_eIgnore;
        rv = DispatchClickEvent(aVisitor.mPresContext, keyEvent, this,
                                false, nullptr, &status);
        if (NS_SUCCEEDED(rv)) {
          aVisitor.mEventStatus = nsEventStatus_eConsumeNoDefault;
        }
      }
    }
    break;

  default:
    // switch not in sync with the optimization switch earlier in this function
    MOZ_ASSERT_UNREACHABLE("switch statements not in sync");
    return NS_ERROR_UNEXPECTED;
  }

  return rv;
}

void
Element::GetLinkTarget(nsAString& aTarget)
{
  aTarget.Truncate();
}

static void
nsDOMTokenListPropertyDestructor(void *aObject, nsAtom *aProperty,
                                 void *aPropertyValue, void *aData)
{
  nsDOMTokenList* list =
    static_cast<nsDOMTokenList*>(aPropertyValue);
  NS_RELEASE(list);
}

static nsStaticAtom* const sPropertiesToTraverseAndUnlink[] =
  {
    nsGkAtoms::sandbox,
    nsGkAtoms::sizes,
    nsGkAtoms::dirAutoSetBy,
    nullptr
  };

// static
nsStaticAtom* const*
Element::HTMLSVGPropertiesToTraverseAndUnlink()
{
  return sPropertiesToTraverseAndUnlink;
}

nsDOMTokenList*
Element::GetTokenList(nsAtom* aAtom,
                      const DOMTokenListSupportedTokenArray aSupportedTokens)
{
#ifdef DEBUG
  const nsStaticAtom* const* props = HTMLSVGPropertiesToTraverseAndUnlink();
  bool found = false;
  for (uint32_t i = 0; props[i]; ++i) {
    if (props[i] == aAtom) {
      found = true;
      break;
    }
  }
  MOZ_ASSERT(found, "Trying to use an unknown tokenlist!");
#endif

  nsDOMTokenList* list = nullptr;
  if (HasProperties()) {
    list = static_cast<nsDOMTokenList*>(GetProperty(aAtom));
  }
  if (!list) {
    list = new nsDOMTokenList(this, aAtom, aSupportedTokens);
    NS_ADDREF(list);
    SetProperty(aAtom, list, nsDOMTokenListPropertyDestructor);
  }
  return list;
}

Element*
Element::Closest(const nsAString& aSelector, ErrorResult& aResult)
{
  const RawServoSelectorList* list = ParseSelectorList(aSelector, aResult);
  if (!list) {
    return nullptr;
  }

  return const_cast<Element*>(Servo_SelectorList_Closest(this, list));
}

bool
Element::Matches(const nsAString& aSelector, ErrorResult& aResult)
{
  const RawServoSelectorList* list = ParseSelectorList(aSelector, aResult);
  if (!list) {
    return false;
  }
  return Servo_SelectorList_Matches(this, list);
}

static const nsAttrValue::EnumTable kCORSAttributeTable[] = {
  // Order matters here
  // See ParseCORSValue
  { "anonymous",       CORS_ANONYMOUS       },
  { "use-credentials", CORS_USE_CREDENTIALS },
  { nullptr,           0 }
};

/* static */ void
Element::ParseCORSValue(const nsAString& aValue,
                        nsAttrValue& aResult)
{
  DebugOnly<bool> success =
    aResult.ParseEnumValue(aValue, kCORSAttributeTable, false,
                           // default value is anonymous if aValue is
                           // not a value we understand
                           &kCORSAttributeTable[0]);
  MOZ_ASSERT(success);
}

/* static */ CORSMode
Element::StringToCORSMode(const nsAString& aValue)
{
  if (aValue.IsVoid()) {
    return CORS_NONE;
  }

  nsAttrValue val;
  Element::ParseCORSValue(aValue, val);
  return CORSMode(val.GetEnumValue());
}

/* static */ CORSMode
Element::AttrValueToCORSMode(const nsAttrValue* aValue)
{
  if (!aValue) {
    return CORS_NONE;
  }

  return CORSMode(aValue->GetEnumValue());
}

static const char*
GetFullscreenError(CallerType aCallerType)
{
  if (!nsContentUtils::IsRequestFullscreenAllowed(aCallerType)) {
    return "FullscreenDeniedNotInputDriven";
  }

  return nullptr;
}

already_AddRefed<Promise>
Element::RequestFullscreen(CallerType aCallerType, ErrorResult& aRv)
{
  auto request = FullscreenRequest::Create(this, aCallerType, aRv);
  RefPtr<Promise> promise = request->GetPromise();

  if (!FeaturePolicyUtils::IsFeatureAllowed(OwnerDoc(),
                                            NS_LITERAL_STRING("fullscreen"))) {
    request->Reject("FullscreenDeniedFeaturePolicy");
    return promise.forget();
  }

  // Only grant fullscreen requests if this is called from inside a trusted
  // event handler (i.e. inside an event handler for a user initiated event).
  // This stops the fullscreen from being abused similar to the popups of old,
  // and it also makes it harder for bad guys' script to go fullscreen and
  // spoof the browser chrome/window and phish logins etc.
  // Note that requests for fullscreen inside a web app's origin are exempt
  // from this restriction.
  if (const char* error = GetFullscreenError(aCallerType)) {
    request->Reject(error);
  } else {
    OwnerDoc()->AsyncRequestFullscreen(std::move(request));
  }
  return promise.forget();
}

void
Element::RequestPointerLock(CallerType aCallerType)
{
  OwnerDoc()->RequestPointerLock(this, aCallerType);
}

already_AddRefed<Flex>
Element::GetAsFlexContainer()
{
  nsIFrame* frame = GetPrimaryFrame();

  // We need the flex frame to compute additional info, and use
  // that annotated version of the frame.
  nsFlexContainerFrame* flexFrame =
    nsFlexContainerFrame::GetFlexFrameWithComputedInfo(frame);

  if (flexFrame) {
    RefPtr<Flex> flex = new Flex(this, flexFrame);
    return flex.forget();
  }
  return nullptr;
}

void
Element::GetGridFragments(nsTArray<RefPtr<Grid>>& aResult)
{
  nsGridContainerFrame* frame =
    nsGridContainerFrame::GetGridFrameWithComputedInfo(GetPrimaryFrame());

  // If we get a nsGridContainerFrame from the prior call,
  // all the next-in-flow frames will also be nsGridContainerFrames.
  while (frame) {
    aResult.AppendElement(
      new Grid(this, frame)
    );
    frame = static_cast<nsGridContainerFrame*>(frame->GetNextInFlow());
  }
}

already_AddRefed<DOMMatrixReadOnly>
Element::GetTransformToAncestor(Element& aAncestor)
{
  nsIFrame* primaryFrame = GetPrimaryFrame();
  nsIFrame* ancestorFrame = aAncestor.GetPrimaryFrame();

  Matrix4x4 transform;
  if (primaryFrame) {
    // If aAncestor is not actually an ancestor of this (including nullptr),
    // then the call to GetTransformToAncestor will return the transform
    // all the way up through the parent chain.
    transform = nsLayoutUtils::GetTransformToAncestor(primaryFrame,
      ancestorFrame, nsIFrame::IN_CSS_UNITS).GetMatrix();
  }

  DOMMatrixReadOnly* matrix = new DOMMatrix(this, transform);
  RefPtr<DOMMatrixReadOnly> result(matrix);
  return result.forget();
}

already_AddRefed<DOMMatrixReadOnly>
Element::GetTransformToParent()
{
  nsIFrame* primaryFrame = GetPrimaryFrame();

  Matrix4x4 transform;
  if (primaryFrame) {
    nsIFrame* parentFrame = primaryFrame->GetParent();
    transform = nsLayoutUtils::GetTransformToAncestor(primaryFrame,
      parentFrame, nsIFrame::IN_CSS_UNITS).GetMatrix();
  }

  DOMMatrixReadOnly* matrix = new DOMMatrix(this, transform);
  RefPtr<DOMMatrixReadOnly> result(matrix);
  return result.forget();
}

already_AddRefed<DOMMatrixReadOnly>
Element::GetTransformToViewport()
{
  nsIFrame* primaryFrame = GetPrimaryFrame();
  Matrix4x4 transform;
  if (primaryFrame) {
    transform = nsLayoutUtils::GetTransformToAncestor(primaryFrame,
      nsLayoutUtils::GetDisplayRootFrame(primaryFrame), nsIFrame::IN_CSS_UNITS).GetMatrix();
  }

  DOMMatrixReadOnly* matrix = new DOMMatrix(this, transform);
  RefPtr<DOMMatrixReadOnly> result(matrix);
  return result.forget();
}

already_AddRefed<Animation>
Element::Animate(JSContext* aContext,
                 JS::Handle<JSObject*> aKeyframes,
                 const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
                 ErrorResult& aError)
{
  Nullable<ElementOrCSSPseudoElement> target;
  target.SetValue().SetAsElement() = this;
  return Animate(target, aContext, aKeyframes, aOptions, aError);
}

/* static */ already_AddRefed<Animation>
Element::Animate(const Nullable<ElementOrCSSPseudoElement>& aTarget,
                 JSContext* aContext,
                 JS::Handle<JSObject*> aKeyframes,
                 const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
                 ErrorResult& aError)
{
  MOZ_ASSERT(!aTarget.IsNull() &&
             (aTarget.Value().IsElement() ||
              aTarget.Value().IsCSSPseudoElement()),
             "aTarget should be initialized");

  RefPtr<Element> referenceElement;
  if (aTarget.Value().IsElement()) {
    referenceElement = &aTarget.Value().GetAsElement();
  } else {
    referenceElement = aTarget.Value().GetAsCSSPseudoElement().ParentElement();
  }

  nsCOMPtr<nsIGlobalObject> ownerGlobal = referenceElement->GetOwnerGlobal();
  if (!ownerGlobal) {
    aError.Throw(NS_ERROR_FAILURE);
    return nullptr;
  }
  GlobalObject global(aContext, ownerGlobal->GetGlobalJSObject());
  MOZ_ASSERT(!global.Failed());

  // KeyframeEffect constructor doesn't follow the standard Xray calling
  // convention and needs to be called in caller's compartment.
  // This should match to RunConstructorInCallerCompartment attribute in
  // KeyframeEffect.webidl.
  RefPtr<KeyframeEffect> effect =
    KeyframeEffect::Constructor(global, aTarget, aKeyframes, aOptions,
                                aError);
  if (aError.Failed()) {
    return nullptr;
  }

  // Animation constructor follows the standard Xray calling convention and
  // needs to be called in the target element's realm.
  Maybe<JSAutoRealm> ar;
  if (js::GetContextCompartment(aContext) !=
      js::GetObjectCompartment(ownerGlobal->GetGlobalJSObject())) {
    ar.emplace(aContext, ownerGlobal->GetGlobalJSObject());
  }

  AnimationTimeline* timeline = referenceElement->OwnerDoc()->Timeline();
  RefPtr<Animation> animation =
    Animation::Constructor(global, effect,
                           Optional<AnimationTimeline*>(timeline), aError);
  if (aError.Failed()) {
    return nullptr;
  }

  if (aOptions.IsKeyframeAnimationOptions()) {
    animation->SetId(aOptions.GetAsKeyframeAnimationOptions().mId);
  }

  animation->Play(aError, Animation::LimitBehavior::AutoRewind);
  if (aError.Failed()) {
    return nullptr;
  }

  return animation.forget();
}

void
Element::GetAnimations(const AnimationFilter& filter,
                       nsTArray<RefPtr<Animation>>& aAnimations)
{
  nsIDocument* doc = GetComposedDoc();
  if (doc) {
    // We don't need to explicitly flush throttled animations here, since
    // updating the animation style of elements will never affect the set of
    // running animations and it's only the set of running animations that is
    // important here.
    doc->FlushPendingNotifications(
      ChangesToFlush(FlushType::Style, false /* flush animations */));
  }

  Element* elem = this;
  CSSPseudoElementType pseudoType = CSSPseudoElementType::NotPseudo;
  // For animations on generated-content elements, the animations are stored
  // on the parent element.
  if (IsGeneratedContentContainerForBefore()) {
    elem = GetParentElement();
    pseudoType = CSSPseudoElementType::before;
  } else if (IsGeneratedContentContainerForAfter()) {
    elem = GetParentElement();
    pseudoType = CSSPseudoElementType::after;
  }

  if (!elem) {
    return;
  }

  if (!filter.mSubtree ||
      pseudoType == CSSPseudoElementType::before ||
      pseudoType == CSSPseudoElementType::after) {
    GetAnimationsUnsorted(elem, pseudoType, aAnimations);
  } else {
    for (nsIContent* node = this;
         node;
         node = node->GetNextNode(this)) {
      if (!node->IsElement()) {
        continue;
      }
      Element* element = node->AsElement();
      Element::GetAnimationsUnsorted(element, CSSPseudoElementType::NotPseudo,
                                     aAnimations);
      Element::GetAnimationsUnsorted(element, CSSPseudoElementType::before,
                                     aAnimations);
      Element::GetAnimationsUnsorted(element, CSSPseudoElementType::after,
                                     aAnimations);
    }
  }
  aAnimations.Sort(AnimationPtrComparator<RefPtr<Animation>>());
}

/* static */ void
Element::GetAnimationsUnsorted(Element* aElement,
                               CSSPseudoElementType aPseudoType,
                               nsTArray<RefPtr<Animation>>& aAnimations)
{
  MOZ_ASSERT(aPseudoType == CSSPseudoElementType::NotPseudo ||
             aPseudoType == CSSPseudoElementType::after ||
             aPseudoType == CSSPseudoElementType::before,
             "Unsupported pseudo type");
  MOZ_ASSERT(aElement, "Null element");

  EffectSet* effects = EffectSet::GetEffectSet(aElement, aPseudoType);
  if (!effects) {
    return;
  }

  for (KeyframeEffect* effect : *effects) {
    MOZ_ASSERT(effect && effect->GetAnimation(),
               "Only effects associated with an animation should be "
               "added to an element's effect set");
    Animation* animation = effect->GetAnimation();

    MOZ_ASSERT(animation->IsRelevant(),
               "Only relevant animations should be added to an element's "
               "effect set");
    aAnimations.AppendElement(animation);
  }
}

void
Element::GetInnerHTML(nsAString& aInnerHTML, OOMReporter& aError)
{
  GetMarkup(false, aInnerHTML);
}

void
Element::SetInnerHTML(const nsAString& aInnerHTML, nsIPrincipal* aSubjectPrincipal, ErrorResult& aError)
{
  SetInnerHTMLInternal(aInnerHTML, aError);
}

void
Element::GetOuterHTML(nsAString& aOuterHTML)
{
  GetMarkup(true, aOuterHTML);
}

void
Element::SetOuterHTML(const nsAString& aOuterHTML, ErrorResult& aError)
{
  nsCOMPtr<nsINode> parent = GetParentNode();
  if (!parent) {
    return;
  }

  if (parent->NodeType() == DOCUMENT_NODE) {
    aError.Throw(NS_ERROR_DOM_NO_MODIFICATION_ALLOWED_ERR);
    return;
  }

  if (OwnerDoc()->IsHTMLDocument()) {
    nsAtom* localName;
    int32_t namespaceID;
    if (parent->IsElement()) {
      localName = parent->NodeInfo()->NameAtom();
      namespaceID = parent->NodeInfo()->NamespaceID();
    } else {
      NS_ASSERTION(parent->NodeType() == DOCUMENT_FRAGMENT_NODE,
        "How come the parent isn't a document, a fragment or an element?");
      localName = nsGkAtoms::body;
      namespaceID = kNameSpaceID_XHTML;
    }
    RefPtr<DocumentFragment> fragment =
      new DocumentFragment(OwnerDoc()->NodeInfoManager());
    nsContentUtils::ParseFragmentHTML(aOuterHTML,
                                      fragment,
                                      localName,
                                      namespaceID,
                                      OwnerDoc()->GetCompatibilityMode() ==
                                        eCompatibility_NavQuirks,
                                      true);
    parent->ReplaceChild(*fragment, *this, aError);
    return;
  }

  nsCOMPtr<nsINode> context;
  if (parent->IsElement()) {
    context = parent;
  } else {
    NS_ASSERTION(parent->NodeType() == DOCUMENT_FRAGMENT_NODE,
      "How come the parent isn't a document, a fragment or an element?");
    RefPtr<mozilla::dom::NodeInfo> info =
      OwnerDoc()->NodeInfoManager()->GetNodeInfo(nsGkAtoms::body,
                                                 nullptr,
                                                 kNameSpaceID_XHTML,
                                                 ELEMENT_NODE);
    context = NS_NewHTMLBodyElement(info.forget(), FROM_PARSER_FRAGMENT);
  }

  RefPtr<DocumentFragment> fragment =
    nsContentUtils::CreateContextualFragment(context, aOuterHTML, true, aError);
  if (aError.Failed()) {
    return;
  }
  parent->ReplaceChild(*fragment, *this, aError);
}

enum nsAdjacentPosition {
  eBeforeBegin,
  eAfterBegin,
  eBeforeEnd,
  eAfterEnd
};

void
Element::InsertAdjacentHTML(const nsAString& aPosition, const nsAString& aText,
                            ErrorResult& aError)
{
  nsAdjacentPosition position;
  if (aPosition.LowerCaseEqualsLiteral("beforebegin")) {
    position = eBeforeBegin;
  } else if (aPosition.LowerCaseEqualsLiteral("afterbegin")) {
    position = eAfterBegin;
  } else if (aPosition.LowerCaseEqualsLiteral("beforeend")) {
    position = eBeforeEnd;
  } else if (aPosition.LowerCaseEqualsLiteral("afterend")) {
    position = eAfterEnd;
  } else {
    aError.Throw(NS_ERROR_DOM_SYNTAX_ERR);
    return;
  }

  nsCOMPtr<nsIContent> destination;
  if (position == eBeforeBegin || position == eAfterEnd) {
    destination = GetParent();
    if (!destination) {
      aError.Throw(NS_ERROR_DOM_NO_MODIFICATION_ALLOWED_ERR);
      return;
    }
  } else {
    destination = this;
  }

  nsIDocument* doc = OwnerDoc();

  // Needed when insertAdjacentHTML is used in combination with contenteditable
  mozAutoDocUpdate updateBatch(doc, true);
  nsAutoScriptLoaderDisabler sld(doc);

  // Batch possible DOMSubtreeModified events.
  mozAutoSubtreeModified subtree(doc, nullptr);

  // Parse directly into destination if possible
  if (doc->IsHTMLDocument() && !OwnerDoc()->MayHaveDOMMutationObservers() &&
      (position == eBeforeEnd ||
       (position == eAfterEnd && !GetNextSibling()) ||
       (position == eAfterBegin && !GetFirstChild()))) {
    int32_t oldChildCount = destination->GetChildCount();
    int32_t contextNs = destination->GetNameSpaceID();
    nsAtom* contextLocal = destination->NodeInfo()->NameAtom();
    if (contextLocal == nsGkAtoms::html && contextNs == kNameSpaceID_XHTML) {
      // For compat with IE6 through IE9. Willful violation of HTML5 as of
      // 2011-04-06. CreateContextualFragment does the same already.
      // Spec bug: http://www.w3.org/Bugs/Public/show_bug.cgi?id=12434
      contextLocal = nsGkAtoms::body;
    }
    aError = nsContentUtils::ParseFragmentHTML(aText,
                                               destination,
                                               contextLocal,
                                               contextNs,
                                               doc->GetCompatibilityMode() ==
                                                 eCompatibility_NavQuirks,
                                               true);
    // HTML5 parser has notified, but not fired mutation events.
    nsContentUtils::FireMutationEventsForDirectParsing(doc, destination,
                                                       oldChildCount);
    return;
  }

  // couldn't parse directly
  RefPtr<DocumentFragment> fragment =
    nsContentUtils::CreateContextualFragment(destination, aText, true, aError);
  if (aError.Failed()) {
    return;
  }

  // Suppress assertion about node removal mutation events that can't have
  // listeners anyway, because no one has had the chance to register mutation
  // listeners on the fragment that comes from the parser.
  nsAutoScriptBlockerSuppressNodeRemoved scriptBlocker;

  nsAutoMutationBatch mb(destination, true, false);
  switch (position) {
    case eBeforeBegin:
      destination->InsertBefore(*fragment, this, aError);
      break;
    case eAfterBegin:
      static_cast<nsINode*>(this)->InsertBefore(*fragment, GetFirstChild(),
                                                aError);
      break;
    case eBeforeEnd:
      static_cast<nsINode*>(this)->AppendChild(*fragment, aError);
      break;
    case eAfterEnd:
      destination->InsertBefore(*fragment, GetNextSibling(), aError);
      break;
  }
}

nsINode*
Element::InsertAdjacent(const nsAString& aWhere,
                        nsINode* aNode,
                        ErrorResult& aError)
{
  if (aWhere.LowerCaseEqualsLiteral("beforebegin")) {
    nsCOMPtr<nsINode> parent = GetParentNode();
    if (!parent) {
      return nullptr;
    }
    parent->InsertBefore(*aNode, this, aError);
  } else if (aWhere.LowerCaseEqualsLiteral("afterbegin")) {
    nsCOMPtr<nsINode> refNode = GetFirstChild();
    static_cast<nsINode*>(this)->InsertBefore(*aNode, refNode, aError);
  } else if (aWhere.LowerCaseEqualsLiteral("beforeend")) {
    static_cast<nsINode*>(this)->AppendChild(*aNode, aError);
  } else if (aWhere.LowerCaseEqualsLiteral("afterend")) {
    nsCOMPtr<nsINode> parent = GetParentNode();
    if (!parent) {
      return nullptr;
    }
    nsCOMPtr<nsINode> refNode = GetNextSibling();
    parent->InsertBefore(*aNode, refNode, aError);
  } else {
    aError.Throw(NS_ERROR_DOM_SYNTAX_ERR);
    return nullptr;
  }

  return aError.Failed() ? nullptr : aNode;
}

Element*
Element::InsertAdjacentElement(const nsAString& aWhere,
                               Element& aElement,
                               ErrorResult& aError) {
  nsINode* newNode = InsertAdjacent(aWhere, &aElement, aError);
  MOZ_ASSERT(!newNode || newNode->IsElement());

  return newNode ? newNode->AsElement() : nullptr;
}

void
Element::InsertAdjacentText(
  const nsAString& aWhere, const nsAString& aData, ErrorResult& aError)
{
  RefPtr<nsTextNode> textNode = OwnerDoc()->CreateTextNode(aData);
  InsertAdjacent(aWhere, textNode, aError);
}

TextEditor*
Element::GetTextEditorInternal()
{
  nsCOMPtr<nsITextControlElement> textCtrl = do_QueryInterface(this);
  return textCtrl ? textCtrl->GetTextEditor() : nullptr;
}

nsresult
Element::SetBoolAttr(nsAtom* aAttr, bool aValue)
{
  if (aValue) {
    return SetAttr(kNameSpaceID_None, aAttr, EmptyString(), true);
  }

  return UnsetAttr(kNameSpaceID_None, aAttr, true);
}

void
Element::GetEnumAttr(nsAtom* aAttr,
                     const char* aDefault,
                     nsAString& aResult) const
{
  GetEnumAttr(aAttr, aDefault, aDefault, aResult);
}

void
Element::GetEnumAttr(nsAtom* aAttr,
                     const char* aDefaultMissing,
                     const char* aDefaultInvalid,
                     nsAString& aResult) const
{
  const nsAttrValue* attrVal = mAttrs.GetAttr(aAttr);

  aResult.Truncate();

  if (!attrVal) {
    if (aDefaultMissing) {
      AppendASCIItoUTF16(nsDependentCString(aDefaultMissing), aResult);
    } else {
      SetDOMStringToNull(aResult);
    }
  } else {
    if (attrVal->Type() == nsAttrValue::eEnum) {
      attrVal->GetEnumString(aResult, true);
    } else if (aDefaultInvalid) {
      AppendASCIItoUTF16(nsDependentCString(aDefaultInvalid), aResult);
    }
  }
}

void
Element::SetOrRemoveNullableStringAttr(nsAtom* aName, const nsAString& aValue,
                                       ErrorResult& aError)
{
  if (DOMStringIsNull(aValue)) {
    UnsetAttr(aName, aError);
  } else {
    SetAttr(aName, aValue, aError);
  }
}

Directionality
Element::GetComputedDirectionality() const
{
  nsIFrame* frame = GetPrimaryFrame();
  if (frame) {
    return frame->StyleVisibility()->mDirection == NS_STYLE_DIRECTION_LTR
             ? eDir_LTR : eDir_RTL;
  }

  return GetDirectionality();
}

float
Element::FontSizeInflation()
{
  nsIFrame* frame = GetPrimaryFrame();
  if (!frame) {
    return -1.0;
  }

  if (nsLayoutUtils::FontSizeInflationEnabled(frame->PresContext())) {
    return nsLayoutUtils::FontSizeInflationFor(frame);
  }

  return 1.0;
}

net::ReferrerPolicy
Element::GetReferrerPolicyAsEnum()
{
  if (IsHTMLElement()) {
    const nsAttrValue* referrerValue = GetParsedAttr(nsGkAtoms::referrerpolicy);
    return ReferrerPolicyFromAttr(referrerValue);
  }
  return net::RP_Unset;
}

net::ReferrerPolicy
Element::ReferrerPolicyFromAttr(const nsAttrValue* aValue)
{
  if (aValue && aValue->Type() == nsAttrValue::eEnum) {
    return net::ReferrerPolicy(aValue->GetEnumValue());
  }
  return net::RP_Unset;
}

already_AddRefed<nsDOMStringMap>
Element::Dataset()
{
  nsDOMSlots *slots = DOMSlots();

  if (!slots->mDataset) {
    // mDataset is a weak reference so assignment will not AddRef.
    // AddRef is called before returning the pointer.
    slots->mDataset = new nsDOMStringMap(this);
  }

  RefPtr<nsDOMStringMap> ret = slots->mDataset;
  return ret.forget();
}

void
Element::ClearDataset()
{
  nsDOMSlots *slots = GetExistingDOMSlots();

  MOZ_ASSERT(slots && slots->mDataset,
             "Slots should exist and dataset should not be null.");
  slots->mDataset = nullptr;
}

enum nsPreviousIntersectionThreshold {
  eUninitialized = -2,
  eNonIntersecting = -1
};

static void
IntersectionObserverPropertyDtor(void* aObject, nsAtom* aPropertyName,
                                 void* aPropertyValue, void* aData)
{
  Element* element = static_cast<Element*>(aObject);
  IntersectionObserverList* observers =
    static_cast<IntersectionObserverList*>(aPropertyValue);
  for (auto iter = observers->Iter(); !iter.Done(); iter.Next()) {
    DOMIntersectionObserver* observer = iter.Key();
    observer->UnlinkTarget(*element);
  }
  delete observers;
}

void
Element::RegisterIntersectionObserver(DOMIntersectionObserver* aObserver)
{
  IntersectionObserverList* observers =
    static_cast<IntersectionObserverList*>(
      GetProperty(nsGkAtoms::intersectionobserverlist)
    );

  if (!observers) {
    observers = new IntersectionObserverList();
    observers->Put(aObserver, eUninitialized);
    SetProperty(nsGkAtoms::intersectionobserverlist, observers,
                IntersectionObserverPropertyDtor, true);
    return;
  }

  observers->LookupForAdd(aObserver).OrInsert([]() {
    // Value can be:
    //   -2:   Makes sure next calculated threshold always differs, leading to a
    //         notification task being scheduled.
    //   -1:   Non-intersecting.
    //   >= 0: Intersecting, valid index of aObserver->mThresholds.
    return eUninitialized;
  });
}

void
Element::UnregisterIntersectionObserver(DOMIntersectionObserver* aObserver)
{
  IntersectionObserverList* observers =
    static_cast<IntersectionObserverList*>(
      GetProperty(nsGkAtoms::intersectionobserverlist)
    );
  if (observers) {
    observers->Remove(aObserver);
  }
}

void
Element::UnlinkIntersectionObservers()
{
  IntersectionObserverList* observers =
    static_cast<IntersectionObserverList*>(
      GetProperty(nsGkAtoms::intersectionobserverlist)
    );
  if (!observers) {
    return;
  }
  for (auto iter = observers->Iter(); !iter.Done(); iter.Next()) {
    DOMIntersectionObserver* observer = iter.Key();
    observer->UnlinkTarget(*this);
  }
  observers->Clear();
}

bool
Element::UpdateIntersectionObservation(DOMIntersectionObserver* aObserver, int32_t aThreshold)
{
  IntersectionObserverList* observers =
    static_cast<IntersectionObserverList*>(
      GetProperty(nsGkAtoms::intersectionobserverlist)
    );
  if (!observers) {
    return false;
  }
  bool updated = false;
  if (auto entry = observers->Lookup(aObserver)) {
    updated = entry.Data() != aThreshold;
    entry.Data() = aThreshold;
  }
  return updated;
}

template<class T> void
Element::GetCustomInterface(nsGetterAddRefs<T> aResult)
{
  nsCOMPtr<nsISupports> iface =
    CustomElementRegistry::CallGetCustomInterface(this, NS_GET_TEMPLATE_IID(T));
  if (iface) {
    CallQueryInterface(iface, static_cast<T**>(aResult));
  }
}

void
Element::ClearServoData(nsIDocument* aDoc) {
  MOZ_ASSERT(aDoc);
  if (HasServoData()) {
    Servo_Element_ClearData(this);
  } else {
    UnsetFlags(kAllServoDescendantBits | NODE_NEEDS_FRAME);
  }
  // Since this element is losing its servo data, nothing under it may have
  // servo data either, so we can forget restyles rooted at this element. This
  // is necessary for correctness, since we invoke ClearServoData in various
  // places where an element's flattened tree parent changes, and such a change
  // may also make an element invalid to be used as a restyle root.
  if (aDoc->GetServoRestyleRoot() == this) {
    aDoc->ClearServoRestyleRoot();
  }
}

void
Element::SetCustomElementData(CustomElementData* aData)
{
  SetHasCustomElementData();

  if (aData->mState != CustomElementData::State::eCustom) {
    SetDefined(false);
  }

  nsExtendedDOMSlots *slots = ExtendedDOMSlots();
  MOZ_ASSERT(!slots->mCustomElementData, "Custom element data may not be changed once set.");
  #if DEBUG
    // We assert only XUL usage, since web may pass whatever as 'is' value
    if (NodeInfo()->NamespaceID() == kNameSpaceID_XUL) {
      nsAtom* name = NodeInfo()->NameAtom();
      nsAtom* type = aData->GetCustomElementType();
      // Check to see if the tag name is a dashed name.
      if (nsContentUtils::IsNameWithDash(name)) {
        // Assert that a tag name with dashes is always an autonomous custom
        // element.
        MOZ_ASSERT(type == name);
      } else {
        // Could still be an autonomous custom element with a non-dashed tag name.
        // Need the check below for sure.
        if (type != name) {
          // Assert that the name of the built-in custom element type is always
          // a dashed name.
          MOZ_ASSERT(nsContentUtils::IsNameWithDash(type));
        }
      }
    }
  #endif
  slots->mCustomElementData = aData;
}

CustomElementDefinition*
Element::GetCustomElementDefinition() const
{
  CustomElementData* data = GetCustomElementData();
  if (!data) {
    return nullptr;
  }

  return data->GetCustomElementDefinition();
}

void
Element::SetCustomElementDefinition(CustomElementDefinition* aDefinition)
{
  CustomElementData* data = GetCustomElementData();
  MOZ_ASSERT(data);

  data->SetCustomElementDefinition(aDefinition);
}

MOZ_DEFINE_MALLOC_SIZE_OF(ServoElementMallocSizeOf)
MOZ_DEFINE_MALLOC_ENCLOSING_SIZE_OF(ServoElementMallocEnclosingSizeOf)

void
Element::AddSizeOfExcludingThis(nsWindowSizes& aSizes, size_t* aNodeSize) const
{
  FragmentOrElement::AddSizeOfExcludingThis(aSizes, aNodeSize);

  if (HasServoData()) {
    // Measure the ElementData object itself.
    aSizes.mLayoutElementDataObjects +=
      aSizes.mState.mMallocSizeOf(mServoData.Get());

    // Measure mServoData, excluding the ComputedValues. This measurement
    // counts towards the element's size. We use ServoElementMallocSizeOf and
    // ServoElementMallocEnclosingSizeOf rather than |aState.mMallocSizeOf| to
    // better distinguish in DMD's output the memory measured within Servo
    // code.
    *aNodeSize +=
      Servo_Element_SizeOfExcludingThisAndCVs(ServoElementMallocSizeOf,
                                              ServoElementMallocEnclosingSizeOf,
                                              &aSizes.mState.mSeenPtrs, this);

    // Now measure just the ComputedValues (and style structs) under
    // mServoData. This counts towards the relevant fields in |aSizes|.
    RefPtr<ComputedStyle> sc;
    if (Servo_Element_HasPrimaryComputedValues(this)) {
      sc = Servo_Element_GetPrimaryComputedValues(this).Consume();
      if (!aSizes.mState.HaveSeenPtr(sc.get())) {
        sc->AddSizeOfIncludingThis(aSizes, &aSizes.mLayoutComputedValuesDom);
      }

      for (size_t i = 0; i < nsCSSPseudoElements::kEagerPseudoCount; i++) {
        if (Servo_Element_HasPseudoComputedValues(this, i)) {
          sc = Servo_Element_GetPseudoComputedValues(this, i).Consume();
          if (!aSizes.mState.HaveSeenPtr(sc.get())) {
            sc->AddSizeOfIncludingThis(aSizes,
                                       &aSizes.mLayoutComputedValuesDom);
          }
        }
      }
    }
  }
}

#ifdef DEBUG
static bool
BitsArePropagated(const Element* aElement, uint32_t aBits, nsINode* aRestyleRoot)
{
  const Element* curr = aElement;
  while (curr) {
    if (curr == aRestyleRoot) {
      return true;
    }
    if (!curr->HasAllFlags(aBits)) {
      return false;
    }
    nsINode* parentNode = curr->GetParentNode();
    curr = curr->GetFlattenedTreeParentElementForStyle();
    MOZ_ASSERT_IF(!curr,
                  parentNode == aElement->OwnerDoc() ||
                  parentNode == parentNode->OwnerDoc()->GetRootElement());
  }
  return true;
}
#endif

static inline void
AssertNoBitsPropagatedFrom(nsINode* aRoot)
{
#ifdef DEBUG
  if (!aRoot || !aRoot->IsElement()) {
    return;
  }

  auto* element = aRoot->GetFlattenedTreeParentElementForStyle();
  while (element) {
    MOZ_ASSERT(!element->HasAnyOfFlags(Element::kAllServoDescendantBits));
    element = element->GetFlattenedTreeParentElementForStyle();
  }
#endif
}

// Sets `aBits` on `aElement` and all of its flattened-tree ancestors up to and
// including aStopAt or the root element (whichever is encountered first), and
// as long as `aBitsToStopAt` isn't found anywhere in the chain.
static inline Element*
PropagateBits(Element* aElement, uint32_t aBits, nsINode* aStopAt, uint32_t aBitsToStopAt)
{
  Element* curr = aElement;
  while (curr && !curr->HasAllFlags(aBitsToStopAt)) {
    curr->SetFlags(aBits);
    if (curr == aStopAt) {
      break;
    }
    curr = curr->GetFlattenedTreeParentElementForStyle();
  }

  if (aBitsToStopAt != aBits && curr) {
    curr->SetFlags(aBits);
  }

  return curr;
}

// Notes that a given element is "dirty" with respect to the given descendants
// bit (which may be one of dirty descendants, dirty animation descendants, or
// need frame construction for descendants).
//
// This function operates on the dirty element itself, despite the fact that the
// bits are generally used to describe descendants. This allows restyle roots
// to be scoped as tightly as possible. On the first call to NoteDirtyElement
// since the last restyle, we don't set any descendant bits at all, and just set
// the element as the restyle root.
//
// Because the style traversal handles multiple tasks (styling, animation-ticking,
// and lazy frame construction), there are potentially three separate kinds of
// dirtiness to track. Rather than maintaining three separate restyle roots, we
// use a single root, and always bubble it up to be the nearest common ancestor
// of all the dirty content in the tree. This means that we need to track the
// types of dirtiness that the restyle root corresponds to, so
// SetServoRestyleRoot accepts a bitfield along with an element.
//
// The overall algorithm is as follows:
// * When the first dirty element is noted, we just set as the restyle root.
// * When additional dirty elements are noted, we propagate the given bit up
//   the tree, until we either reach the restyle root or the document root.
// * If we reach the document root, we then propagate the bits associated with
//   the restyle root up the tree until we cross the path of the new root. Once
//   we find this common ancestor, we record it as the restyle root, and then
//   clear the bits between the new restyle root and the document root.
// * If we have dirty content beneath multiple "document style traversal roots"
//   (which are the main DOM + each piece of document-level native-anoymous
//   content), we set the restyle root to the nsINode of the document itself.
//   This is the bail-out case where we traverse everything.
//
// Note that, since we track a root, we try to optimize the case where an
// element under the current root is dirtied, that's why we don't trivially use
// `nsContentUtils::GetCommonFlattenedTreeAncestorForStyle`.
static void
NoteDirtyElement(Element* aElement, uint32_t aBits)
{
  MOZ_ASSERT(aElement->IsInComposedDoc());

  // Check the existing root early on, since it may allow us to short-circuit
  // before examining the parent chain.
  nsIDocument* doc = aElement->GetComposedDoc();
  nsINode* existingRoot = doc->GetServoRestyleRoot();
  if (existingRoot == aElement) {
    doc->SetServoRestyleRootDirtyBits(doc->GetServoRestyleRootDirtyBits() | aBits);
    return;
  }

  nsINode* parent = aElement->GetFlattenedTreeParentNodeForStyle();
  if (!parent) {
    // The element is not in the flattened tree, bail.
    return;
  }

  if (MOZ_LIKELY(parent->IsElement())) {
    // If our parent is unstyled, we can inductively assume that it will be
    // traversed when the time is right, and that the traversal will reach us
    // when it happens. Nothing left to do.
    if (!parent->AsElement()->HasServoData()) {
      return;
    }

    // Similarly, if our parent already has the bit we're propagating, we can
    // assume everything is already set up.
    if (parent->HasAllFlags(aBits)) {
      return;
    }

    // If the parent is styled but is display:none, we're done.
    //
    // We can't check for a frame here, since <frame> elements inside <frameset>
    // still need to generate a frame, even if they're display: none. :(
    //
    // The servo traversal doesn't keep style data under display: none subtrees,
    // so in order for it to not need to cleanup each time anything happens in a
    // display: none subtree, we keep it clean.
    //
    // Also, we can't be much more smarter about using the parent's frame in
    // order to avoid work here, because since the style system keeps style data
    // in, e.g., subtrees under a leaf frame, missing restyles and such in there
    // has observable behavior via getComputedStyle, for example.
    if (Servo_Element_IsDisplayNone(parent->AsElement())) {
      return;
    }
  }

  if (nsIPresShell* shell = doc->GetShell()) {
    shell->EnsureStyleFlush();
  }

  MOZ_ASSERT(parent->IsElement() || parent == doc);

  // The bit checks below rely on this to arrive to useful conclusions about the
  // shape of the tree.
  AssertNoBitsPropagatedFrom(existingRoot);

  // If there's no existing restyle root, or if the root is already aElement,
  // just note the root+bits and return.
  if (!existingRoot) {
    doc->SetServoRestyleRoot(aElement, aBits);
    return;
  }

  // There is an existing restyle root - walk up the tree from our element,
  // propagating bits as we go.
  const bool reachedDocRoot =
    !parent->IsElement() ||
    !PropagateBits(parent->AsElement(), aBits, existingRoot, aBits);

  uint32_t existingBits = doc->GetServoRestyleRootDirtyBits();
  if (!reachedDocRoot || existingRoot == doc) {
      // We're a descendant of the existing root. All that's left to do is to
      // make sure the bit we propagated is also registered on the root.
      doc->SetServoRestyleRoot(existingRoot, existingBits | aBits);
  } else {
    // We reached the root without crossing the pre-existing restyle root. We
    // now need to find the nearest common ancestor, so climb up from the
    // existing root, extending bits along the way.
    Element* rootParent = existingRoot->GetFlattenedTreeParentElementForStyle();
    // We can stop at the first occurrence of `aBits` in order to find the
    // common ancestor.
    if (Element* commonAncestor = PropagateBits(rootParent, existingBits, aElement, aBits)) {
      MOZ_ASSERT(commonAncestor == aElement ||
                 commonAncestor == nsContentUtils::GetCommonFlattenedTreeAncestorForStyle(aElement, rootParent));

      // We found a common ancestor. Make that the new style root, and clear the
      // bits between the new style root and the document root.
      doc->SetServoRestyleRoot(commonAncestor, existingBits | aBits);
      Element* curr = commonAncestor;
      while ((curr = curr->GetFlattenedTreeParentElementForStyle())) {
        MOZ_ASSERT(curr->HasAllFlags(aBits));
        curr->UnsetFlags(aBits);
      }
      AssertNoBitsPropagatedFrom(commonAncestor);
    } else {
      // We didn't find a common ancestor element. That means we're descended
      // from two different document style roots, so the common ancestor is the
      // document.
      doc->SetServoRestyleRoot(doc, existingBits | aBits);
    }
  }

  // See the comment in nsIDocument::SetServoRestyleRoot about the !IsElement()
  // check there. Same justification here.
  MOZ_ASSERT(aElement == doc->GetServoRestyleRoot() ||
             !doc->GetServoRestyleRoot()->IsElement() ||
             nsContentUtils::ContentIsFlattenedTreeDescendantOfForStyle(
               aElement, doc->GetServoRestyleRoot()));
  MOZ_ASSERT(aElement == doc->GetServoRestyleRoot() ||
             !doc->GetServoRestyleRoot()->IsElement() ||
             !parent->IsElement() ||
             BitsArePropagated(parent->AsElement(), aBits, doc->GetServoRestyleRoot()));
  MOZ_ASSERT(doc->GetServoRestyleRootDirtyBits() & aBits);
}

void
Element::NoteDirtySubtreeForServo()
{
  MOZ_ASSERT(IsInComposedDoc());
  MOZ_ASSERT(HasServoData());

  nsIDocument* doc = GetComposedDoc();
  nsINode* existingRoot = doc->GetServoRestyleRoot();
  uint32_t existingBits = existingRoot ? doc->GetServoRestyleRootDirtyBits() : 0;

  if (existingRoot &&
      existingRoot->IsElement() &&
      existingRoot != this &&
      nsContentUtils::ContentIsFlattenedTreeDescendantOfForStyle(
        existingRoot->AsElement(), this)) {
    PropagateBits(existingRoot->AsElement()->GetFlattenedTreeParentElementForStyle(),
                  existingBits,
                  this,
                  existingBits);

    doc->ClearServoRestyleRoot();
  }

  NoteDirtyElement(this, existingBits | ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO);
}

void
Element::NoteDirtyForServo()
{
  NoteDirtyElement(this, ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO);
}

void
Element::NoteAnimationOnlyDirtyForServo()
{
  NoteDirtyElement(this, ELEMENT_HAS_ANIMATION_ONLY_DIRTY_DESCENDANTS_FOR_SERVO);
}

void
Element::NoteDescendantsNeedFramesForServo()
{
  // Since lazy frame construction can be required for non-element nodes, this
  // Note() method operates on the parent of the frame-requiring content, unlike
  // the other Note() methods above (which operate directly on the element that
  // needs processing).
  NoteDirtyElement(this, NODE_DESCENDANTS_NEED_FRAMES);
  SetFlags(NODE_DESCENDANTS_NEED_FRAMES);
}