dom/base/ShadowRoot.cpp
author Emilio Cobos Álvarez <emilio@crisal.io>
Mon, 07 May 2018 19:11:13 +0200
changeset 417133 3b491d808696692d2f48fb7ff333e579a8312583
parent 416540 39788dcbd008d4782533e192ba426b1bc746a33f
child 417501 950004745b55410e8f56c65d9e46eb200a4b5e74
permissions -rw-r--r--
Bug 1459688: Properly traverse the stylesheet list of the shadow root. r=smaug This is sound because the unlink implementation of the stylesheet drops the preserved wrapper, and there are no strong references back to any node from the stylesheet or any of the non-unlinked members. This almost is the same setup that works for document sheets. We need to account for a double reference in case the sheet is applicable because Servo keeps another reference to it in that case, instead of in the StyleSet / PresShell. Added the testcase as a crashtest, in the hopes that if it regresses leak reporting on automation will catch it. MozReview-Commit-ID: Kcc5oaOvP9A

/* -*- 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/. */

#include "mozilla/Preferences.h"
#include "mozilla/dom/ShadowRoot.h"
#include "mozilla/dom/ShadowRootBinding.h"
#include "mozilla/dom/DocumentFragment.h"
#include "ChildIterator.h"
#include "nsContentUtils.h"
#include "nsIStyleSheetLinkingElement.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/HTMLSlotElement.h"
#include "nsXBLPrototypeBinding.h"
#include "mozilla/EventDispatcher.h"
#include "mozilla/StyleSheet.h"
#include "mozilla/StyleSheetInlines.h"

using namespace mozilla;
using namespace mozilla::dom;

NS_IMPL_CYCLE_COLLECTION_CLASS(ShadowRoot)

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(ShadowRoot, DocumentFragment)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mStyleSheets)
  for (StyleSheet* sheet : tmp->mStyleSheets) {
    // mServoStyles keeps another reference to it if applicable.
    if (sheet->IsApplicable()) {
      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mServoStyles->sheets[i]");
      cb.NoteXPCOMChild(sheet);
    }
  }
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDOMStyleSheets)
  for (auto iter = tmp->mIdentifierMap.ConstIter(); !iter.Done();
       iter.Next()) {
    iter.Get()->Traverse(&cb);
  }
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ShadowRoot)
  if (tmp->GetHost()) {
    tmp->GetHost()->RemoveMutationObserver(tmp);
  }
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mDOMStyleSheets)
  tmp->mIdentifierMap.Clear();
NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(DocumentFragment)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ShadowRoot)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIContent)
  NS_INTERFACE_MAP_ENTRY(nsIMutationObserver)
NS_INTERFACE_MAP_END_INHERITING(DocumentFragment)

NS_IMPL_ADDREF_INHERITED(ShadowRoot, DocumentFragment)
NS_IMPL_RELEASE_INHERITED(ShadowRoot, DocumentFragment)

ShadowRoot::ShadowRoot(Element* aElement, ShadowRootMode aMode,
                       already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
  : DocumentFragment(aNodeInfo)
  , DocumentOrShadowRoot(*this)
  , mMode(aMode)
  , mServoStyles(Servo_AuthorStyles_Create())
  , mIsComposedDocParticipant(false)
{
  SetHost(aElement);

  // Nodes in a shadow tree should never store a value
  // in the subtree root pointer, nodes in the shadow tree
  // track the subtree root using GetContainingShadow().
  ClearSubtreeRootPointer();

  SetFlags(NODE_IS_IN_SHADOW_TREE);

  ExtendedDOMSlots()->mBindingParent = aElement;
  ExtendedDOMSlots()->mContainingShadow = this;

  // Add the ShadowRoot as a mutation observer on the host to watch
  // for mutations because the insertion points in this ShadowRoot
  // may need to be updated when the host children are modified.
  GetHost()->AddMutationObserver(this);
}

ShadowRoot::~ShadowRoot()
{
  if (auto* host = GetHost()) {
    // mHost may have been unlinked.
    host->RemoveMutationObserver(this);
  }

  if (IsComposedDocParticipant()) {
    OwnerDoc()->RemoveComposedDocShadowRoot(*this);
  }

  MOZ_DIAGNOSTIC_ASSERT(!OwnerDoc()->IsComposedDocShadowRoot(*this));

  UnsetFlags(NODE_IS_IN_SHADOW_TREE);

  // nsINode destructor expects mSubtreeRoot == this.
  SetSubtreeRootPointer(this);
}

void
ShadowRoot::SetIsComposedDocParticipant(bool aIsComposedDocParticipant)
{
  bool changed = mIsComposedDocParticipant != aIsComposedDocParticipant;
  mIsComposedDocParticipant = aIsComposedDocParticipant;
  if (!changed) {
    return;
  }

  nsIDocument* doc = OwnerDoc();
  if (IsComposedDocParticipant()) {
    doc->AddComposedDocShadowRoot(*this);
  } else {
    doc->RemoveComposedDocShadowRoot(*this);
  }
}

JSObject*
ShadowRoot::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
{
  return mozilla::dom::ShadowRootBinding::Wrap(aCx, this, aGivenProto);
}

void
ShadowRoot::CloneInternalDataFrom(ShadowRoot* aOther)
{
  size_t sheetCount = aOther->SheetCount();
  for (size_t i = 0; i < sheetCount; ++i) {
    StyleSheet* sheet = aOther->SheetAt(i);
    if (sheet->IsApplicable()) {
      RefPtr<StyleSheet> clonedSheet =
        sheet->Clone(nullptr, nullptr, nullptr, nullptr);
      if (clonedSheet) {
        AppendStyleSheet(*clonedSheet.get());
      }
    }
  }
}

void
ShadowRoot::InvalidateStyleAndLayoutOnSubtree(Element* aElement)
{
  MOZ_ASSERT(aElement);

  if (!IsComposedDocParticipant()) {
    return;
  }

  MOZ_ASSERT(GetComposedDoc() == OwnerDoc());

  nsIPresShell* shell = OwnerDoc()->GetShell();
  if (!shell) {
    return;
  }

  shell->DestroyFramesForAndRestyle(aElement);
}

void
ShadowRoot::AddSlot(HTMLSlotElement* aSlot)
{
  MOZ_ASSERT(aSlot);

  // Note that if name attribute missing, the slot is a default slot.
  nsAutoString name;
  aSlot->GetName(name);

  nsTArray<HTMLSlotElement*>* currentSlots = mSlotMap.LookupOrAdd(name);
  MOZ_ASSERT(currentSlots);

  HTMLSlotElement* oldSlot = currentSlots->SafeElementAt(0);

  TreeOrderComparator comparator;
  currentSlots->InsertElementSorted(aSlot, comparator);

  HTMLSlotElement* currentSlot = currentSlots->ElementAt(0);
  if (currentSlot != aSlot) {
    return;
  }

  if (oldSlot && oldSlot != currentSlot) {
    // Move assigned nodes from old slot to new slot.
    InvalidateStyleAndLayoutOnSubtree(oldSlot);
    const nsTArray<RefPtr<nsINode>>& assignedNodes = oldSlot->AssignedNodes();
    bool doEnqueueSlotChange = false;
    while (assignedNodes.Length() > 0) {
      nsINode* assignedNode = assignedNodes[0];

      oldSlot->RemoveAssignedNode(assignedNode);
      currentSlot->AppendAssignedNode(assignedNode);
      doEnqueueSlotChange = true;
    }

    if (doEnqueueSlotChange) {
      oldSlot->EnqueueSlotChangeEvent();
      currentSlot->EnqueueSlotChangeEvent();
    }
  } else {
    bool doEnqueueSlotChange = false;
    // Otherwise add appropriate nodes to this slot from the host.
    for (nsIContent* child = GetHost()->GetFirstChild();
         child;
         child = child->GetNextSibling()) {
      nsAutoString slotName;
      if (child->IsElement()) {
        child->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::slot, slotName);
      }
      if (!child->IsSlotable() || !slotName.Equals(name)) {
        continue;
      }
      doEnqueueSlotChange = true;
      currentSlot->AppendAssignedNode(child);
    }

    if (doEnqueueSlotChange) {
      currentSlot->EnqueueSlotChangeEvent();
    }
  }
}

void
ShadowRoot::RemoveSlot(HTMLSlotElement* aSlot)
{
  MOZ_ASSERT(aSlot);

  nsAutoString name;
  aSlot->GetName(name);

  SlotArray* currentSlots = mSlotMap.Get(name);
  MOZ_DIAGNOSTIC_ASSERT(currentSlots && currentSlots->Contains(aSlot),
                        "Slot to deregister wasn't found?");
  if (currentSlots->Length() == 1) {
    MOZ_ASSERT(currentSlots->ElementAt(0) == aSlot);
    mSlotMap.Remove(name);

    if (!aSlot->AssignedNodes().IsEmpty()) {
      aSlot->ClearAssignedNodes();
      aSlot->EnqueueSlotChangeEvent();
    }

    return;
  }

  const bool wasFirstSlot = currentSlots->ElementAt(0) == aSlot;
  currentSlots->RemoveElement(aSlot);

  // Move assigned nodes from removed slot to the next slot in
  // tree order with the same name.
  if (!wasFirstSlot) {
    return;
  }

  HTMLSlotElement* replacementSlot = currentSlots->ElementAt(0);
  const nsTArray<RefPtr<nsINode>>& assignedNodes = aSlot->AssignedNodes();
  bool slottedNodesChanged = !assignedNodes.IsEmpty();
  while (!assignedNodes.IsEmpty()) {
    nsINode* assignedNode = assignedNodes[0];

    aSlot->RemoveAssignedNode(assignedNode);
    replacementSlot->AppendAssignedNode(assignedNode);
  }

  if (slottedNodesChanged) {
    aSlot->EnqueueSlotChangeEvent();
    replacementSlot->EnqueueSlotChangeEvent();
  }
}

// FIXME(emilio): There's a bit of code duplication between this and the
// equivalent ServoStyleSet methods, it'd be nice to not duplicate it...
void
ShadowRoot::RuleAdded(StyleSheet& aSheet, css::Rule& aRule)
{
  if (mStyleRuleMap) {
    mStyleRuleMap->RuleAdded(aSheet, aRule);
  }

  Servo_AuthorStyles_ForceDirty(mServoStyles.get());
  ApplicableRulesChanged();
}

void
ShadowRoot::RuleRemoved(StyleSheet& aSheet, css::Rule& aRule)
{
  if (mStyleRuleMap) {
    mStyleRuleMap->RuleRemoved(aSheet, aRule);
  }

  Servo_AuthorStyles_ForceDirty(mServoStyles.get());
  ApplicableRulesChanged();
}

void
ShadowRoot::RuleChanged(StyleSheet&, css::Rule*) {
  Servo_AuthorStyles_ForceDirty(mServoStyles.get());
  ApplicableRulesChanged();
}

void
ShadowRoot::ApplicableRulesChanged()
{
  if (!IsComposedDocParticipant()) {
    return;
  }

  nsIDocument* doc = OwnerDoc();
  if (nsIPresShell* shell = doc->GetShell()) {
    doc->BeginUpdate(UPDATE_STYLE);
    shell->RecordShadowStyleChange(*this);
    doc->EndUpdate(UPDATE_STYLE);
  }
}

void
ShadowRoot::InsertSheetAt(size_t aIndex, StyleSheet& aSheet)
{
  DocumentOrShadowRoot::InsertSheetAt(aIndex, aSheet);
  if (aSheet.IsApplicable()) {
    InsertSheetIntoAuthorData(aIndex, aSheet);
  }
}

void
ShadowRoot::AppendStyleSheet(StyleSheet& aSheet)
{
  DocumentOrShadowRoot::AppendStyleSheet(aSheet);
  if (aSheet.IsApplicable()) {
    Servo_AuthorStyles_AppendStyleSheet(mServoStyles.get(), &aSheet);
    if (mStyleRuleMap) {
      mStyleRuleMap->SheetAdded(aSheet);
    }
    ApplicableRulesChanged();
  }
}

void
ShadowRoot::InsertSheet(StyleSheet* aSheet, nsIContent* aLinkingContent)
{
  nsCOMPtr<nsIStyleSheetLinkingElement>
    linkingElement = do_QueryInterface(aLinkingContent);

  // FIXME(emilio, bug 1410578): <link> should probably also be allowed here.
  MOZ_ASSERT(linkingElement, "The only styles in a ShadowRoot should come "
                             "from <style>.");

  linkingElement->SetStyleSheet(aSheet); // This sets the ownerNode on the sheet

  // Find the correct position to insert into the style sheet list (must
  // be in tree order).
  for (size_t i = 0; i <= SheetCount(); i++) {
    if (i == SheetCount()) {
      AppendStyleSheet(*aSheet);
      return;
    }

    StyleSheet* sheet = SheetAt(i);
    nsINode* sheetOwningNode = sheet->GetOwnerNode();
    if (nsContentUtils::PositionIsBefore(aLinkingContent, sheetOwningNode)) {
      InsertSheetAt(i, *aSheet);
      return;
    }
  }
}

void
ShadowRoot::InsertSheetIntoAuthorData(size_t aIndex, StyleSheet& aSheet)
{
  MOZ_ASSERT(SheetAt(aIndex) == &aSheet);
  MOZ_ASSERT(aSheet.IsApplicable());

  if (mStyleRuleMap) {
    mStyleRuleMap->SheetAdded(aSheet);
  }

  for (size_t i = aIndex + 1; i < SheetCount(); ++i) {
    StyleSheet* beforeSheet = SheetAt(i);
    if (!beforeSheet->IsApplicable()) {
      continue;
    }

    Servo_AuthorStyles_InsertStyleSheetBefore(
      mServoStyles.get(), &aSheet, beforeSheet);
    ApplicableRulesChanged();
    return;
  }

  Servo_AuthorStyles_AppendStyleSheet(mServoStyles.get(), &aSheet);
  ApplicableRulesChanged();
}

void
ShadowRoot::StyleSheetApplicableStateChanged(StyleSheet& aSheet, bool aApplicable)
{
  MOZ_ASSERT(mStyleSheets.Contains(&aSheet));
  if (aApplicable) {
    int32_t index = IndexOfSheet(aSheet);
    MOZ_RELEASE_ASSERT(index >= 0);
    InsertSheetIntoAuthorData(size_t(index), aSheet);
  } else {
    if (mStyleRuleMap) {
      mStyleRuleMap->SheetRemoved(aSheet);
    }
    Servo_AuthorStyles_RemoveStyleSheet(mServoStyles.get(), &aSheet);
    ApplicableRulesChanged();
  }
}

void
ShadowRoot::RemoveSheet(StyleSheet* aSheet)
{
  DocumentOrShadowRoot::RemoveSheet(*aSheet);
  if (aSheet->IsApplicable()) {
    if (mStyleRuleMap) {
      mStyleRuleMap->SheetRemoved(*aSheet);
    }
    Servo_AuthorStyles_RemoveStyleSheet(mServoStyles.get(), aSheet);
    ApplicableRulesChanged();
  }
}

void
ShadowRoot::AddToIdTable(Element* aElement, nsAtom* aId)
{
  nsIdentifierMapEntry* entry = mIdentifierMap.PutEntry(aId);
  if (entry) {
    entry->AddIdElement(aElement);
  }
}

void
ShadowRoot::RemoveFromIdTable(Element* aElement, nsAtom* aId)
{
  nsIdentifierMapEntry* entry = mIdentifierMap.GetEntry(aId);
  if (entry) {
    entry->RemoveIdElement(aElement);
    if (entry->IsEmpty()) {
      mIdentifierMap.RemoveEntry(entry);
    }
  }
}

void
ShadowRoot::GetEventTargetParent(EventChainPreVisitor& aVisitor)
{
  aVisitor.mCanHandle = true;
  aVisitor.mRootOfClosedTree = IsClosed();
  // Inform that we're about to exit the current scope.
  aVisitor.mRelatedTargetRetargetedInCurrentScope = false;

  // https://dom.spec.whatwg.org/#ref-for-get-the-parent%E2%91%A6
  if (!aVisitor.mEvent->mFlags.mComposed) {
    nsCOMPtr<nsIContent> originalTarget =
      do_QueryInterface(aVisitor.mEvent->mOriginalTarget);
    if (originalTarget->GetContainingShadow() == this) {
      // If we do stop propagation, we still want to propagate
      // the event to chrome (nsPIDOMWindow::GetParentTarget()).
      // The load event is special in that we don't ever propagate it
      // to chrome.
      nsCOMPtr<nsPIDOMWindowOuter> win = OwnerDoc()->GetWindow();
      EventTarget* parentTarget = win && aVisitor.mEvent->mMessage != eLoad
        ? win->GetParentTarget() : nullptr;

      aVisitor.SetParentTarget(parentTarget, true);
      return;
    }
  }

  nsIContent* shadowHost = GetHost();
  aVisitor.SetParentTarget(shadowHost, false);

  nsCOMPtr<nsIContent> content(do_QueryInterface(aVisitor.mEvent->mTarget));
  if (content && content->GetBindingParent() == shadowHost) {
    aVisitor.mEventTargetAtParent = shadowHost;
  }
}

ShadowRoot::SlotAssignment
ShadowRoot::SlotAssignmentFor(nsIContent* aContent)
{
  nsAutoString slotName;
  // Note that if slot attribute is missing, assign it to the first default
  // slot, if exists.
  if (aContent->IsElement()) {
    aContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::slot, slotName);
  }

  nsTArray<HTMLSlotElement*>* slots = mSlotMap.Get(slotName);
  if (!slots) {
    return { };
  }

  HTMLSlotElement* slot = slots->ElementAt(0);
  MOZ_ASSERT(slot);

  // Find the appropriate position in the assigned node list for the
  // newly assigned content.
  const nsTArray<RefPtr<nsINode>>& assignedNodes = slot->AssignedNodes();
  nsIContent* currentContent = GetHost()->GetFirstChild();
  Maybe<uint32_t> insertionIndex;
  for (uint32_t i = 0; i < assignedNodes.Length(); i++) {
    // Seek through the host's explicit children until the
    // assigned content is found.
    while (currentContent && currentContent != assignedNodes[i]) {
      if (currentContent == aContent) {
        insertionIndex.emplace(i);
        break;
      }

      currentContent = currentContent->GetNextSibling();
    }

    if (insertionIndex) {
      break;
    }
  }

  return { slot, insertionIndex };
}

void
ShadowRoot::MaybeReassignElement(Element* aElement)
{
  MOZ_ASSERT(aElement->GetParent() == GetHost());
  HTMLSlotElement* oldSlot = aElement->GetAssignedSlot();
  SlotAssignment assignment = SlotAssignmentFor(aElement);

  if (assignment.mSlot == oldSlot) {
    // Nothing to do here.
    return;
  }

  if (IsComposedDocParticipant()) {
    if (nsIPresShell* shell = OwnerDoc()->GetShell()) {
      shell->SlotAssignmentWillChange(*aElement, oldSlot, assignment.mSlot);
    }
  }

  if (oldSlot) {
    oldSlot->RemoveAssignedNode(aElement);
    oldSlot->EnqueueSlotChangeEvent();
  }

  if (assignment.mSlot) {
    if (assignment.mIndex) {
      assignment.mSlot->InsertAssignedNode(*assignment.mIndex, aElement);
    } else {
      assignment.mSlot->AppendAssignedNode(aElement);
    }
    assignment.mSlot->EnqueueSlotChangeEvent();
  }
}

Element*
ShadowRoot::GetActiveElement()
{
  return GetRetargetedFocusedElement();
}

void
ShadowRoot::GetInnerHTML(nsAString& aInnerHTML)
{
  GetMarkup(false, aInnerHTML);
}

void
ShadowRoot::SetInnerHTML(const nsAString& aInnerHTML, ErrorResult& aError)
{
  SetInnerHTMLInternal(aInnerHTML, aError);
}

void
ShadowRoot::AttributeChanged(Element* aElement,
                             int32_t aNameSpaceID,
                             nsAtom* aAttribute,
                             int32_t aModType,
                             const nsAttrValue* aOldValue)
{
  if (aNameSpaceID != kNameSpaceID_None || aAttribute != nsGkAtoms::slot) {
    return;
  }

  if (aElement->GetParent() != GetHost()) {
    return;
  }

  MaybeReassignElement(aElement);
}

void
ShadowRoot::ContentAppended(nsIContent* aFirstNewContent)
{
  for (nsIContent* content = aFirstNewContent;
       content;
       content = content->GetNextSibling()) {
    ContentInserted(content);
  }
}

void
ShadowRoot::ContentInserted(nsIContent* aChild)
{
  // Check to ensure that the child not an anonymous subtree root because
  // even though its parent could be the host it may not be in the host's child
  // list.
  if (aChild->IsRootOfAnonymousSubtree()) {
    return;
  }

  if (!aChild->IsSlotable()) {
    return;
  }

  if (aChild->GetParent() == GetHost()) {
    SlotAssignment assignment = SlotAssignmentFor(aChild);
    if (!assignment.mSlot) {
      return;
    }

    // Fallback content will go away, let layout know.
    if (assignment.mSlot->AssignedNodes().IsEmpty()) {
      InvalidateStyleAndLayoutOnSubtree(assignment.mSlot);
    }

    if (assignment.mIndex) {
      assignment.mSlot->InsertAssignedNode(*assignment.mIndex, aChild);
    } else {
      assignment.mSlot->AppendAssignedNode(aChild);
    }
    assignment.mSlot->EnqueueSlotChangeEvent();
    return;
  }

  // If parent's root is a shadow root, and parent is a slot whose assigned
  // nodes is the empty list, then run signal a slot change for parent.
  HTMLSlotElement* slot = HTMLSlotElement::FromNodeOrNull(aChild->GetParent());
  if (slot && slot->GetContainingShadow() == this &&
      slot->AssignedNodes().IsEmpty()) {
    slot->EnqueueSlotChangeEvent();
  }
}

void
ShadowRoot::ContentRemoved(nsIContent* aChild, nsIContent* aPreviousSibling)
{
  // Check to ensure that the child not an anonymous subtree root because
  // even though its parent could be the host it may not be in the host's child
  // list.
 if (aChild->IsRootOfAnonymousSubtree()) {
    return;
  }

  if (!aChild->IsSlotable()) {
    return;
  }

  if (aChild->GetParent() == GetHost()) {
    if (HTMLSlotElement* slot = aChild->GetAssignedSlot()) {
      // If the slot is going to start showing fallback content, we need to tell
      // layout about it.
      if (slot->AssignedNodes().Length() == 1) {
        InvalidateStyleAndLayoutOnSubtree(slot);
      }
      slot->RemoveAssignedNode(aChild);
      slot->EnqueueSlotChangeEvent();
    }
    return;
  }

  // If parent's root is a shadow root, and parent is a slot whose assigned
  // nodes is the empty list, then run signal a slot change for parent.
  HTMLSlotElement* slot = HTMLSlotElement::FromNodeOrNull(aChild->GetParent());
  if (slot && slot->GetContainingShadow() == this &&
      slot->AssignedNodes().IsEmpty()) {
    slot->EnqueueSlotChangeEvent();
  }
}

ServoStyleRuleMap&
ShadowRoot::ServoStyleRuleMap()
{
  if (!mStyleRuleMap) {
    mStyleRuleMap = MakeUnique<mozilla::ServoStyleRuleMap>();
  }
  mStyleRuleMap->EnsureTable(*this);
  return *mStyleRuleMap;
}

nsresult
ShadowRoot::Clone(mozilla::dom::NodeInfo *aNodeInfo, nsINode **aResult,
                  bool aPreallocateChildren) const
{
  *aResult = nullptr;
  return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
}