1 files changed, 718 insertions, 0 deletions
diff --git a/dom/base/ShadowRoot.cpp b/dom/base/ShadowRoot.cpp
new file mode 100644
index 0000000000..8414fe4dc3
--- /dev/null
+++ b/dom/base/ShadowRoot.cpp
@@ -0,0 +1,718 @@
+/* -*- 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/BindContext.h"
+#include "mozilla/dom/ShadowRoot.h"
+#include "mozilla/dom/DocumentFragment.h"
+#include "ChildIterator.h"
+#include "nsContentUtils.h"
+#include "nsWindowSizes.h"
+#include "mozilla/dom/DirectionalityUtils.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/HTMLSlotElement.h"
+#include "mozilla/dom/TreeOrderedArrayInlines.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/IdentifierMapEntry.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/PresShellInlines.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/ServoStyleRuleMap.h"
+#include "mozilla/StyleSheet.h"
+#include "mozilla/StyleSheetInlines.h"
+#include "mozilla/dom/StyleSheetList.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(ShadowRoot)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(ShadowRoot, DocumentFragment)
+  DocumentOrShadowRoot::Traverse(tmp, cb);
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ShadowRoot)
+  DocumentOrShadowRoot::Unlink(tmp);
+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(nsIRadioGroupContainer)
+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(std::move(aNodeInfo)),
+      DocumentOrShadowRoot(this),
+      mMode(aMode),
+      mIsUAWidget(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);
+  Bind();
+
+  ExtendedDOMSlots()->mContainingShadow = this;
+}
+
+ShadowRoot::~ShadowRoot() {
+  if (IsInComposedDoc()) {
+    OwnerDoc()->RemoveComposedDocShadowRoot(*this);
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(!OwnerDoc()->IsComposedDocShadowRoot(*this));
+
+  UnsetFlags(NODE_IS_IN_SHADOW_TREE);
+
+  // nsINode destructor expects mSubtreeRoot == this.
+  SetSubtreeRootPointer(this);
+}
+
+MOZ_DEFINE_MALLOC_SIZE_OF(ShadowRootAuthorStylesMallocSizeOf)
+MOZ_DEFINE_MALLOC_ENCLOSING_SIZE_OF(ShadowRootAuthorStylesMallocEnclosingSizeOf)
+
+void ShadowRoot::AddSizeOfExcludingThis(nsWindowSizes& aSizes,
+                                        size_t* aNodeSize) const {
+  DocumentFragment::AddSizeOfExcludingThis(aSizes, aNodeSize);
+  DocumentOrShadowRoot::AddSizeOfExcludingThis(aSizes);
+  aSizes.mLayoutShadowDomAuthorStyles += Servo_AuthorStyles_SizeOfIncludingThis(
+      ShadowRootAuthorStylesMallocSizeOf,
+      ShadowRootAuthorStylesMallocEnclosingSizeOf, mServoStyles.get());
+}
+
+JSObject* ShadowRoot::WrapNode(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) {
+  return mozilla::dom::ShadowRoot_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+void ShadowRoot::CloneInternalDataFrom(ShadowRoot* aOther) {
+  if (aOther->IsUAWidget()) {
+    SetIsUAWidget();
+  }
+
+  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, this, nullptr);
+      if (clonedSheet) {
+        AppendStyleSheet(*clonedSheet.get());
+      }
+    }
+  }
+  CloneAdoptedSheetsFrom(*aOther);
+}
+
+nsresult ShadowRoot::Bind() {
+  MOZ_ASSERT(!IsInComposedDoc(), "Forgot to unbind?");
+  if (Host()->IsInComposedDoc()) {
+    SetIsConnected(true);
+    Document* doc = OwnerDoc();
+    doc->AddComposedDocShadowRoot(*this);
+    // If our stylesheets somehow mutated when we were disconnected, we need to
+    // ensure that our style data gets flushed as appropriate.
+    if (mServoStyles && Servo_AuthorStyles_IsDirty(mServoStyles.get())) {
+      doc->RecordShadowStyleChange(*this);
+    }
+  }
+
+  BindContext context(*this);
+  for (nsIContent* child = GetFirstChild(); child;
+       child = child->GetNextSibling()) {
+    nsresult rv = child->BindToTree(context, *this);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  return NS_OK;
+}
+
+void ShadowRoot::Unbind() {
+  if (IsInComposedDoc()) {
+    SetIsConnected(false);
+    OwnerDoc()->RemoveComposedDocShadowRoot(*this);
+  }
+
+  for (nsIContent* child = GetFirstChild(); child;
+       child = child->GetNextSibling()) {
+    child->UnbindFromTree(false);
+  }
+}
+
+void ShadowRoot::Unattach() {
+  MOZ_ASSERT(!HasSlots(), "Won't work!");
+  if (!GetHost()) {
+    // It is possible that we've been unlinked already. In such case host
+    // should have called Unbind and ShadowRoot's own unlink.
+    return;
+  }
+
+  Unbind();
+  SetHost(nullptr);
+}
+
+void ShadowRoot::InvalidateStyleAndLayoutOnSubtree(Element* aElement) {
+  MOZ_ASSERT(aElement);
+  Document* doc = GetComposedDoc();
+  if (!doc) {
+    return;
+  }
+
+  PresShell* presShell = doc->GetPresShell();
+  if (!presShell) {
+    return;
+  }
+
+  presShell->DestroyFramesForAndRestyle(aElement);
+}
+
+void ShadowRoot::PartAdded(const Element& aPart) {
+  MOZ_ASSERT(aPart.HasPartAttribute());
+  MOZ_ASSERT(!mParts.Contains(&aPart));
+  mParts.AppendElement(&aPart);
+}
+
+void ShadowRoot::PartRemoved(const Element& aPart) {
+  MOZ_ASSERT(mParts.Contains(&aPart));
+  mParts.RemoveElement(&aPart);
+  MOZ_ASSERT(!mParts.Contains(&aPart));
+}
+
+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);
+
+  SlotArray& currentSlots = *mSlotMap.LookupOrAdd(name);
+
+  size_t index = currentSlots.Insert(*aSlot);
+  if (index != 0) {
+    return;
+  }
+
+  HTMLSlotElement* oldSlot = currentSlots->SafeElementAt(1);
+  if (oldSlot) {
+    MOZ_DIAGNOSTIC_ASSERT(oldSlot != aSlot);
+
+    // 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->AsContent());
+      aSlot->AppendAssignedNode(*assignedNode->AsContent());
+      doEnqueueSlotChange = true;
+    }
+
+    if (doEnqueueSlotChange) {
+      oldSlot->EnqueueSlotChangeEvent();
+      aSlot->EnqueueSlotChangeEvent();
+      SlotStateChanged(oldSlot);
+      SlotStateChanged(aSlot);
+    }
+  } 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 (auto* element = Element::FromNode(*child)) {
+        element->GetAttr(nsGkAtoms::slot, slotName);
+      }
+      if (!child->IsSlotable() || !slotName.Equals(name)) {
+        continue;
+      }
+      doEnqueueSlotChange = true;
+      aSlot->AppendAssignedNode(*child);
+    }
+
+    if (doEnqueueSlotChange) {
+      aSlot->EnqueueSlotChangeEvent();
+      SlotStateChanged(aSlot);
+    }
+  }
+}
+
+void ShadowRoot::RemoveSlot(HTMLSlotElement* aSlot) {
+  MOZ_ASSERT(aSlot);
+
+  nsAutoString name;
+  aSlot->GetName(name);
+
+  MOZ_ASSERT(mSlotMap.Get(name));
+
+  SlotArray& currentSlots = *mSlotMap.Get(name);
+  MOZ_DIAGNOSTIC_ASSERT(currentSlots->Contains(aSlot),
+                        "Slot to de-register wasn't found?");
+  if (currentSlots->Length() == 1) {
+    MOZ_ASSERT(currentSlots->ElementAt(0) == aSlot);
+
+    InvalidateStyleAndLayoutOnSubtree(aSlot);
+
+    mSlotMap.Remove(name);
+    if (!aSlot->AssignedNodes().IsEmpty()) {
+      aSlot->ClearAssignedNodes();
+      aSlot->EnqueueSlotChangeEvent();
+    }
+
+    return;
+  }
+
+  const bool wasFirstSlot = currentSlots->ElementAt(0) == aSlot;
+  currentSlots.RemoveElement(*aSlot);
+  if (!wasFirstSlot) {
+    return;
+  }
+
+  // Move assigned nodes from removed slot to the next slot in
+  // tree order with the same name.
+  InvalidateStyleAndLayoutOnSubtree(aSlot);
+  HTMLSlotElement* replacementSlot = currentSlots->ElementAt(0);
+  const nsTArray<RefPtr<nsINode>>& assignedNodes = aSlot->AssignedNodes();
+  if (assignedNodes.IsEmpty()) {
+    return;
+  }
+
+  InvalidateStyleAndLayoutOnSubtree(replacementSlot);
+  while (!assignedNodes.IsEmpty()) {
+    nsINode* assignedNode = assignedNodes[0];
+
+    aSlot->RemoveAssignedNode(*assignedNode->AsContent());
+    replacementSlot->AppendAssignedNode(*assignedNode->AsContent());
+  }
+
+  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 (!aSheet.IsApplicable()) {
+    return;
+  }
+
+  MOZ_ASSERT(mServoStyles);
+  if (mStyleRuleMap) {
+    mStyleRuleMap->RuleAdded(aSheet, aRule);
+  }
+
+  if (aRule.IsIncompleteImportRule()) {
+    return;
+  }
+
+  Servo_AuthorStyles_ForceDirty(mServoStyles.get());
+  ApplicableRulesChanged();
+}
+
+void ShadowRoot::RuleRemoved(StyleSheet& aSheet, css::Rule& aRule) {
+  if (!aSheet.IsApplicable()) {
+    return;
+  }
+
+  MOZ_ASSERT(mServoStyles);
+  if (mStyleRuleMap) {
+    mStyleRuleMap->RuleRemoved(aSheet, aRule);
+  }
+  Servo_AuthorStyles_ForceDirty(mServoStyles.get());
+  ApplicableRulesChanged();
+}
+
+void ShadowRoot::RuleChanged(StyleSheet& aSheet, css::Rule*,
+                             StyleRuleChangeKind) {
+  if (!aSheet.IsApplicable()) {
+    return;
+  }
+
+  MOZ_ASSERT(mServoStyles);
+  Servo_AuthorStyles_ForceDirty(mServoStyles.get());
+  ApplicableRulesChanged();
+}
+
+void ShadowRoot::ImportRuleLoaded(CSSImportRule&, StyleSheet& aSheet) {
+  if (mStyleRuleMap) {
+    mStyleRuleMap->SheetAdded(aSheet);
+  }
+
+  if (!aSheet.IsApplicable()) {
+    return;
+  }
+
+  // TODO(emilio): Could handle it like a regular sheet insertion, I guess, to
+  // avoid throwing away the whole style data.
+  Servo_AuthorStyles_ForceDirty(mServoStyles.get());
+  ApplicableRulesChanged();
+}
+
+// We don't need to do anything else than forwarding to the document if
+// necessary.
+void ShadowRoot::SheetCloned(StyleSheet& aSheet) {
+  if (Document* doc = GetComposedDoc()) {
+    if (PresShell* shell = doc->GetPresShell()) {
+      shell->StyleSet()->SheetCloned(aSheet);
+    }
+  }
+}
+
+void ShadowRoot::ApplicableRulesChanged() {
+  if (Document* doc = GetComposedDoc()) {
+    doc->RecordShadowStyleChange(*this);
+  }
+}
+
+void ShadowRoot::InsertSheetAt(size_t aIndex, StyleSheet& aSheet) {
+  DocumentOrShadowRoot::InsertSheetAt(aIndex, aSheet);
+  if (aSheet.IsApplicable()) {
+    InsertSheetIntoAuthorData(aIndex, aSheet, mStyleSheets);
+  }
+}
+
+StyleSheet* FirstApplicableAdoptedStyleSheet(
+    const nsTArray<RefPtr<StyleSheet>>& aList) {
+  size_t i = 0;
+  for (StyleSheet* sheet : aList) {
+    // Deal with duplicate sheets by only considering the last one.
+    if (sheet->IsApplicable() && MOZ_LIKELY(aList.LastIndexOf(sheet) == i)) {
+      return sheet;
+    }
+    i++;
+  }
+  return nullptr;
+}
+
+void ShadowRoot::InsertSheetIntoAuthorData(
+    size_t aIndex, StyleSheet& aSheet,
+    const nsTArray<RefPtr<StyleSheet>>& aList) {
+  MOZ_ASSERT(aSheet.IsApplicable());
+  MOZ_ASSERT(aList[aIndex] == &aSheet);
+  MOZ_ASSERT(aList.LastIndexOf(&aSheet) == aIndex);
+  MOZ_ASSERT(&aList == &mAdoptedStyleSheets || &aList == &mStyleSheets);
+
+  if (!mServoStyles) {
+    mServoStyles = Servo_AuthorStyles_Create().Consume();
+  }
+
+  if (mStyleRuleMap) {
+    mStyleRuleMap->SheetAdded(aSheet);
+  }
+
+  auto changedOnExit =
+      mozilla::MakeScopeExit([&] { ApplicableRulesChanged(); });
+
+  for (size_t i = aIndex + 1; i < aList.Length(); ++i) {
+    StyleSheet* beforeSheet = aList.ElementAt(i);
+    if (!beforeSheet->IsApplicable()) {
+      continue;
+    }
+
+    // If this is a duplicate adopted stylesheet that is not in the right
+    // position (the last one) then we skip over it. Otherwise we're done.
+    if (&aList == &mAdoptedStyleSheets &&
+        MOZ_UNLIKELY(aList.LastIndexOf(beforeSheet) != i)) {
+      continue;
+    }
+
+    Servo_AuthorStyles_InsertStyleSheetBefore(mServoStyles.get(), &aSheet,
+                                              beforeSheet);
+    return;
+  }
+
+  if (mAdoptedStyleSheets.IsEmpty() || &aList == &mAdoptedStyleSheets) {
+    Servo_AuthorStyles_AppendStyleSheet(mServoStyles.get(), &aSheet);
+    return;
+  }
+
+  if (auto* before = FirstApplicableAdoptedStyleSheet(mAdoptedStyleSheets)) {
+    Servo_AuthorStyles_InsertStyleSheetBefore(mServoStyles.get(), &aSheet,
+                                              before);
+  } else {
+    Servo_AuthorStyles_AppendStyleSheet(mServoStyles.get(), &aSheet);
+  }
+}
+
+// FIXME(emilio): This needs to notify document observers and such,
+// presumably.
+void ShadowRoot::StyleSheetApplicableStateChanged(StyleSheet& aSheet) {
+  auto& sheetList = aSheet.IsConstructed() ? mAdoptedStyleSheets : mStyleSheets;
+  int32_t index = sheetList.LastIndexOf(&aSheet);
+  if (index < 0) {
+    // NOTE(emilio): @import sheets are handled in the relevant RuleAdded
+    // notification, which only notifies after the sheet is loaded.
+    //
+    // This setup causes weirdness in other places, we may want to fix this in
+    // bug 1465031.
+    MOZ_DIAGNOSTIC_ASSERT(aSheet.GetParentSheet(),
+                          "It'd better be an @import sheet");
+    return;
+  }
+  if (aSheet.IsApplicable()) {
+    InsertSheetIntoAuthorData(size_t(index), aSheet, sheetList);
+  } else {
+    MOZ_ASSERT(mServoStyles);
+    if (mStyleRuleMap) {
+      mStyleRuleMap->SheetRemoved(aSheet);
+    }
+    Servo_AuthorStyles_RemoveStyleSheet(mServoStyles.get(), &aSheet);
+    ApplicableRulesChanged();
+  }
+}
+
+void ShadowRoot::RemoveSheetFromStyles(StyleSheet& aSheet) {
+  MOZ_ASSERT(aSheet.IsApplicable());
+  MOZ_ASSERT(mServoStyles);
+  if (mStyleRuleMap) {
+    mStyleRuleMap->SheetRemoved(aSheet);
+  }
+  Servo_AuthorStyles_RemoveStyleSheet(mServoStyles.get(), &aSheet);
+  ApplicableRulesChanged();
+}
+
+void ShadowRoot::AddToIdTable(Element* aElement, nsAtom* aId) {
+  IdentifierMapEntry* entry = mIdentifierMap.PutEntry(aId);
+  if (entry) {
+    entry->AddIdElement(aElement);
+  }
+}
+
+void ShadowRoot::RemoveFromIdTable(Element* aElement, nsAtom* aId) {
+  IdentifierMapEntry* 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 && 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->GetContainingShadow() == this) {
+    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 (Element* element = Element::FromNode(aContent)) {
+    element->GetAttr(nsGkAtoms::slot, slotName);
+  }
+
+  SlotArray* slots = mSlotMap.Get(slotName);
+  if (!slots) {
+    return {};
+  }
+
+  HTMLSlotElement* slot = (*slots)->ElementAt(0);
+  MOZ_ASSERT(slot);
+
+  if (!aContent.GetNextSibling()) {
+    // aContent is the last child, no need to loop through the assigned nodes,
+    // we're necessarily the last one.
+    //
+    // This prevents multiple appends into the host from getting quadratic.
+    return {slot, Nothing()};
+  }
+
+  // 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();
+  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) {
+        return {slot, Some(i)};
+      }
+      currentContent = currentContent->GetNextSibling();
+    }
+  }
+
+  return {slot, Nothing()};
+}
+
+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 (Document* doc = GetComposedDoc()) {
+    if (RefPtr<PresShell> presShell = doc->GetPresShell()) {
+      presShell->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();
+  }
+
+  SlotAssignedNodeChanged(oldSlot, aElement);
+  SlotAssignedNodeChanged(assignment.mSlot, aElement);
+}
+
+Element* ShadowRoot::GetActiveElement() {
+  return GetRetargetedFocusedElement();
+}
+
+nsINode* ShadowRoot::ImportNodeAndAppendChildAt(nsINode& aParentNode,
+                                                nsINode& aNode, bool aDeep,
+                                                mozilla::ErrorResult& rv) {
+  MOZ_ASSERT(mIsUAWidget);
+
+  if (!aParentNode.IsInUAWidget()) {
+    rv.Throw(NS_ERROR_INVALID_ARG);
+    return nullptr;
+  }
+
+  RefPtr<nsINode> node = OwnerDoc()->ImportNode(aNode, aDeep, rv);
+  if (rv.Failed()) {
+    return nullptr;
+  }
+
+  return aParentNode.AppendChild(*node, rv);
+}
+
+nsINode* ShadowRoot::CreateElementAndAppendChildAt(nsINode& aParentNode,
+                                                   const nsAString& aTagName,
+                                                   mozilla::ErrorResult& rv) {
+  MOZ_ASSERT(mIsUAWidget);
+
+  if (!aParentNode.IsInUAWidget()) {
+    rv.Throw(NS_ERROR_INVALID_ARG);
+    return nullptr;
+  }
+
+  // This option is not exposed to UA Widgets
+  ElementCreationOptionsOrString options;
+
+  RefPtr<nsINode> node = OwnerDoc()->CreateElement(aTagName, options, rv);
+  if (rv.Failed()) {
+    return nullptr;
+  }
+
+  return aParentNode.AppendChild(*node, rv);
+}
+
+void ShadowRoot::MaybeUnslotHostChild(nsIContent& aChild) {
+  // Need to null-check the host because we may be unlinked already.
+  MOZ_ASSERT(!GetHost() || aChild.GetParent() == GetHost());
+
+  HTMLSlotElement* slot = aChild.GetAssignedSlot();
+  if (!slot) {
+    return;
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(!aChild.IsRootOfNativeAnonymousSubtree(),
+                        "How did aChild end up assigned to a slot?");
+  // If the slot is going to start showing fallback content, we need to tell
+  // layout about it.
+  if (slot->AssignedNodes().Length() == 1 && slot->HasChildren()) {
+    InvalidateStyleAndLayoutOnSubtree(slot);
+  }
+
+  slot->RemoveAssignedNode(aChild);
+  slot->EnqueueSlotChangeEvent();
+}
+
+void ShadowRoot::MaybeSlotHostChild(nsIContent& aChild) {
+  MOZ_ASSERT(aChild.GetParent() == GetHost());
+  // 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.IsRootOfNativeAnonymousSubtree()) {
+    return;
+  }
+
+  if (!aChild.IsSlotable()) {
+    return;
+  }
+
+  SlotAssignment assignment = SlotAssignmentFor(aChild);
+  if (!assignment.mSlot) {
+    return;
+  }
+
+  // Fallback content will go away, let layout know.
+  if (assignment.mSlot->AssignedNodes().IsEmpty() &&
+      assignment.mSlot->HasChildren()) {
+    InvalidateStyleAndLayoutOnSubtree(assignment.mSlot);
+  }
+
+  if (assignment.mIndex) {
+    assignment.mSlot->InsertAssignedNode(*assignment.mIndex, aChild);
+  } else {
+    assignment.mSlot->AppendAssignedNode(aChild);
+  }
+  assignment.mSlot->EnqueueSlotChangeEvent();
+  SlotAssignedNodeChanged(assignment.mSlot, aChild);
+}
+
+ServoStyleRuleMap& ShadowRoot::ServoStyleRuleMap() {
+  if (!mStyleRuleMap) {
+    mStyleRuleMap = MakeUnique<mozilla::ServoStyleRuleMap>();
+  }
+  mStyleRuleMap->EnsureTable(*this);
+  return *mStyleRuleMap;
+}
+
+nsresult ShadowRoot::Clone(dom::NodeInfo* aNodeInfo, nsINode** aResult) const {
+  *aResult = nullptr;
+  return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+}