Bug 1828469, part 2: Moved some logic from nsRange to AbstractRange to support StaticRanges in custom highlights. r=masayuki

With this change, Selections are also registered into StaticRanges,
ultimately making them visible to `nsINode::IsSelected()`,
which is necessary to paint them.

Differential Revision: https://phabricator.services.mozilla.com/D175784

dom/base/AbstractRange.cpp

@@ -12,6 +12,7 @@
 #include "mozilla/RangeUtils.h"
 #include "mozilla/dom/Document.h"
 #include "mozilla/dom/StaticRange.h"
+#include "mozilla/dom/Selection.h"
 #include "nsContentUtils.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsGkAtoms.h"
@@ -65,18 +66,73 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(AbstractRange)
   // mStart and mEnd may depend on or be depended on some other members in
   // concrete classes so that they should be unlinked in sub classes.
   NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+  tmp->mSelections.Clear();
+  // Unregistering of the common inclusive ancestors would by design
+  // also happen when the actual implementations unlink `mStart`/`mEnd`.
+  // This may introduce additional overhead which is not needed when unlinking,
+  // therefore this is done here beforehand.
+  if (tmp->mRegisteredClosestCommonInclusiveAncestor) {
+    tmp->UnregisterClosestCommonInclusiveAncestor(
+        tmp->mRegisteredClosestCommonInclusiveAncestor, true);
+  }
+  MOZ_DIAGNOSTIC_ASSERT(!tmp->isInList(),
+                        "Shouldn't be registered now that we're unlinking");
+
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(AbstractRange)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mOwner)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mStart)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mEnd)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRegisteredClosestCommonInclusiveAncestor)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
+void AbstractRange::MarkDescendants(const nsINode& aNode) {
+  // Set NodeIsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection on
+  // aNode's descendants unless aNode is already marked as a range common
+  // ancestor or a descendant of one, in which case all of our descendants have
+  // the bit set already.
+  if (!aNode.IsMaybeSelected()) {
+    // don't set the Descendant bit on |aNode| itself
+    nsINode* node = aNode.GetNextNode(&aNode);
+    while (node) {
+      node->SetDescendantOfClosestCommonInclusiveAncestorForRangeInSelection();
+      if (!node->IsClosestCommonInclusiveAncestorForRangeInSelection()) {
+        node = node->GetNextNode(&aNode);
+      } else {
+        // optimize: skip this sub-tree since it's marked already.
+        node = node->GetNextNonChildNode(&aNode);
+      }
+    }
+  }
+}
+
+void AbstractRange::UnmarkDescendants(const nsINode& aNode) {
+  // Unset NodeIsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection
+  // on aNode's descendants unless aNode is a descendant of another range common
+  // ancestor. Also, exclude descendants of range common ancestors (but not the
+  // common ancestor itself).
+  if (!aNode
+           .IsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection()) {
+    // we know |aNode| doesn't have any bit set
+    nsINode* node = aNode.GetNextNode(&aNode);
+    while (node) {
+      node->ClearDescendantOfClosestCommonInclusiveAncestorForRangeInSelection();
+      if (!node->IsClosestCommonInclusiveAncestorForRangeInSelection()) {
+        node = node->GetNextNode(&aNode);
+      } else {
+        // We found an ancestor of an overlapping range, skip its descendants.
+        node = node->GetNextNonChildNode(&aNode);
+      }
+    }
+  }
+}
+
 // NOTE: If you need to change default value of members of AbstractRange,
 //       update nsRange::Create(nsINode* aNode) and ClearForReuse() too.
 AbstractRange::AbstractRange(nsINode* aNode, bool aIsDynamicRange)
-    : mIsPositioned(false),
+    : mRegisteredClosestCommonInclusiveAncestor(nullptr),
+      mIsPositioned(false),
       mIsGenerated(false),
       mCalledByJS(false),
       mIsDynamicRange(aIsDynamicRange) {
@@ -206,6 +262,122 @@ nsresult AbstractRange::SetStartAndEndInternal(
   return NS_OK;
 }
 
+bool AbstractRange::IsInSelection(const Selection& aSelection) const {
+  return mSelections.Contains(&aSelection);
+}
+
+void AbstractRange::RegisterSelection(Selection& aSelection) {
+  if (IsInSelection(aSelection)) {
+    return;
+  }
+  bool isFirstSelection = mSelections.IsEmpty();
+  mSelections.AppendElement(&aSelection);
+  if (isFirstSelection && !mRegisteredClosestCommonInclusiveAncestor) {
+    nsINode* commonAncestor = GetClosestCommonInclusiveAncestor();
+    MOZ_ASSERT(commonAncestor, "unexpected disconnected nodes");
+    RegisterClosestCommonInclusiveAncestor(commonAncestor);
+  }
+}
+
+const nsTArray<WeakPtr<Selection>>& AbstractRange::GetSelections() const {
+  return mSelections;
+}
+
+void AbstractRange::UnregisterSelection(const Selection& aSelection) {
+  mSelections.RemoveElement(&aSelection);
+  if (mSelections.IsEmpty() && mRegisteredClosestCommonInclusiveAncestor) {
+    UnregisterClosestCommonInclusiveAncestor(
+        mRegisteredClosestCommonInclusiveAncestor, false);
+    MOZ_DIAGNOSTIC_ASSERT(
+        !mRegisteredClosestCommonInclusiveAncestor,
+        "How can we have a registered common ancestor when we "
+        "just unregistered?");
+    MOZ_DIAGNOSTIC_ASSERT(
+        !isInList(),
+        "Shouldn't be registered if we have no "
+        "mRegisteredClosestCommonInclusiveAncestor after unregistering");
+  }
+}
+
+void AbstractRange::RegisterClosestCommonInclusiveAncestor(nsINode* aNode) {
+  MOZ_ASSERT(aNode, "bad arg");
+
+  MOZ_DIAGNOSTIC_ASSERT(IsInAnySelection(),
+                        "registering range not in selection");
+
+  mRegisteredClosestCommonInclusiveAncestor = aNode;
+
+  MarkDescendants(*aNode);
+
+  UniquePtr<LinkedList<AbstractRange>>& ranges =
+      aNode->GetClosestCommonInclusiveAncestorRangesPtr();
+  if (!ranges) {
+    ranges = MakeUnique<LinkedList<AbstractRange>>();
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(!isInList());
+  ranges->insertBack(this);
+  aNode->SetClosestCommonInclusiveAncestorForRangeInSelection();
+}
+
+void AbstractRange::UnregisterClosestCommonInclusiveAncestor(
+    nsINode* aNode, bool aIsUnlinking) {
+  MOZ_ASSERT(aNode, "bad arg");
+  NS_ASSERTION(aNode->IsClosestCommonInclusiveAncestorForRangeInSelection(),
+               "wrong node");
+  MOZ_DIAGNOSTIC_ASSERT(aNode == mRegisteredClosestCommonInclusiveAncestor,
+                        "wrong node");
+  LinkedList<AbstractRange>* ranges =
+      aNode->GetExistingClosestCommonInclusiveAncestorRanges();
+  MOZ_ASSERT(ranges);
+
+  mRegisteredClosestCommonInclusiveAncestor = nullptr;
+
+#ifdef DEBUG
+  bool found = false;
+  for (AbstractRange* range : *ranges) {
+    if (range == this) {
+      found = true;
+      break;
+    }
+  }
+  MOZ_ASSERT(found,
+             "We should be in the list on our registered common ancestor");
+#endif  // DEBUG
+
+  remove();
+
+  // We don't want to waste time unmarking flags on nodes that are
+  // being unlinked anyway.
+  if (!aIsUnlinking && ranges->isEmpty()) {
+    aNode->ClearClosestCommonInclusiveAncestorForRangeInSelection();
+    UnmarkDescendants(*aNode);
+  }
+}
+
+void AbstractRange::UpdateCommonAncestorIfNecessary() {
+  nsINode* oldCommonAncestor = mRegisteredClosestCommonInclusiveAncestor;
+  nsINode* newCommonAncestor = GetClosestCommonInclusiveAncestor();
+  if (newCommonAncestor != oldCommonAncestor) {
+    if (oldCommonAncestor) {
+      UnregisterClosestCommonInclusiveAncestor(oldCommonAncestor, false);
+    }
+    if (newCommonAncestor) {
+      RegisterClosestCommonInclusiveAncestor(newCommonAncestor);
+    } else {
+      MOZ_DIAGNOSTIC_ASSERT(!mIsPositioned, "unexpected disconnected nodes");
+      mSelections.Clear();
+      MOZ_DIAGNOSTIC_ASSERT(
+          !mRegisteredClosestCommonInclusiveAncestor,
+          "How can we have a registered common ancestor when we "
+          "didn't register ourselves?");
+      MOZ_DIAGNOSTIC_ASSERT(!isInList(),
+                            "Shouldn't be registered if we have no "
+                            "mRegisteredClosestCommonInclusiveAncestor");
+    }
+  }
+}
+
 nsINode* AbstractRange::GetParentObject() const { return mOwner; }
 
 JSObject* AbstractRange::WrapObject(JSContext* aCx,

dom/base/AbstractRange.h

@@ -15,6 +15,7 @@
 #include "mozilla/Maybe.h"
 #include "mozilla/RangeBoundary.h"
 #include "mozilla/RefPtr.h"
+#include "mozilla/WeakPtr.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsISupports.h"
 #include "nsWrapperCache.h"
@@ -26,10 +27,14 @@ class nsRange;
 struct JSContext;
 
 namespace mozilla::dom {
-class StaticRange;
 class Document;
+class Selection;
+class StaticRange;
 
-class AbstractRange : public nsISupports, public nsWrapperCache {
+class AbstractRange : public nsISupports,
+                      public nsWrapperCache,
+                      // For linking together selection-associated ranges.
+                      public mozilla::LinkedListElement<AbstractRange> {
  protected:
   explicit AbstractRange(nsINode* aNode, bool aIsDynamicRange);
   virtual ~AbstractRange();
@@ -106,6 +111,27 @@ class AbstractRange : public nsISupports, public nsWrapperCache {
   inline StaticRange* AsStaticRange();
   inline const StaticRange* AsStaticRange() const;
 
+  /**
+   * Return true if this range is part of a Selection object
+   * and isn't detached.
+   */
+  bool IsInAnySelection() const { return !mSelections.IsEmpty(); }
+
+  MOZ_CAN_RUN_SCRIPT void RegisterSelection(
+      mozilla::dom::Selection& aSelection);
+
+  void UnregisterSelection(const mozilla::dom::Selection& aSelection);
+
+  /**
+   * Returns a list of all Selections the range is associated with.
+   */
+  const nsTArray<WeakPtr<Selection>>& GetSelections() const;
+
+  /**
+   * Return true if this range is in |aSelection|.
+   */
+  bool IsInSelection(const mozilla::dom::Selection& aSelection) const;
+
  protected:
   template <typename SPT, typename SRT, typename EPT, typename ERT,
             typename RangeType>
@@ -133,6 +159,21 @@ class AbstractRange : public nsISupports, public nsWrapperCache {
                    << (aRange.mIsDynamicRange ? "true" : "false") << " }";
   }
 
+  /**
+   * https://dom.spec.whatwg.org/#concept-tree-inclusive-ancestor
+   */
+  void RegisterClosestCommonInclusiveAncestor(nsINode* aNode);
+  /**
+   * https://dom.spec.whatwg.org/#concept-tree-inclusive-ancestor
+   */
+  void UnregisterClosestCommonInclusiveAncestor(nsINode* aNode,
+                                                bool aIsUnlinking);
+
+  void UpdateCommonAncestorIfNecessary();
+
+  static void MarkDescendants(const nsINode& aNode);
+  static void UnmarkDescendants(const nsINode& aNode);
+
  private:
   void ClearForReuse();
 
@@ -140,6 +181,13 @@ class AbstractRange : public nsISupports, public nsWrapperCache {
   RefPtr<Document> mOwner;
   RangeBoundary mStart;
   RangeBoundary mEnd;
+
+  // A Range can be part of multiple |Selection|s. This is a very rare use case.
+  AutoTArray<WeakPtr<Selection>, 1> mSelections;
+  // mRegisteredClosestCommonInclusiveAncestor is only non-null when the range
+  // IsInAnySelection().
+  nsCOMPtr<nsINode> mRegisteredClosestCommonInclusiveAncestor;
+
   // `true` if `mStart` and `mEnd` are set for StaticRange or set and valid
   // for nsRange.
   bool mIsPositioned;

dom/base/Element.cpp

@@ -3003,12 +3003,12 @@ void Element::List(FILE* out, int32_t aIndent, const nsCString& aPrefix) const {
           static_cast<unsigned long long>(State().GetInternalValue()));
   fprintf(out, " flags=[%08x]", static_cast<unsigned int>(GetFlags()));
   if (IsClosestCommonInclusiveAncestorForRangeInSelection()) {
-    const LinkedList<nsRange>* ranges =
+    const LinkedList<AbstractRange>* ranges =
         GetExistingClosestCommonInclusiveAncestorRanges();
     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()) {
+      for (const AbstractRange* r = ranges->getFirst(); r; r = r->getNext()) {
         ++count;
       }
     }

dom/base/Selection.cpp

@@ -1234,9 +1234,7 @@ nsresult Selection::StyledRanges::MaybeAddRangeAndTruncateOverlaps(
 
   // Remove all the overlapping ranges
   for (size_t i = startIndex; i < endIndex; ++i) {
-    if (mRanges[i].mRange->IsDynamicRange()) {
-      mRanges[i].mRange->AsDynamicRange()->UnregisterSelection(mSelection);
-    }
+    mRanges[i].mRange->UnregisterSelection(mSelection);
   }
   mRanges.RemoveElementsAt(startIndex, endIndex - startIndex);
 
@@ -1287,9 +1285,8 @@ nsresult Selection::StyledRanges::RemoveRangeAndUnregisterSelection(
   if (idx < 0) return NS_ERROR_DOM_NOT_FOUND_ERR;
 
   mRanges.RemoveElementAt(idx);
-  if (aRange.IsDynamicRange()) {
-    aRange.AsDynamicRange()->UnregisterSelection(mSelection);
-  }
+  aRange.UnregisterSelection(mSelection);
+
   return NS_OK;
 }
 nsresult Selection::RemoveCollapsedRanges() {
@@ -1987,9 +1984,7 @@ void Selection::SetAncestorLimiter(nsIContent* aLimiter) {
 void Selection::StyledRanges::UnregisterSelection() {
   uint32_t count = mRanges.Length();
   for (uint32_t i = 0; i < count; ++i) {
-    if (mRanges[i].mRange->IsDynamicRange()) {
-      mRanges[i].mRange->AsDynamicRange()->UnregisterSelection(mSelection);
-    }
+    mRanges[i].mRange->UnregisterSelection(mSelection);
   }
 }
 
@@ -2237,10 +2232,8 @@ void Selection::AddHighlightRangeAndSelectFramesAndNotifyListeners(
   MOZ_ASSERT(mSelectionType == SelectionType::eHighlight);
 
   mStyledRanges.mRanges.AppendElement(StyledRange{&aRange});
-  if (aRange.IsDynamicRange()) {
-    RefPtr<nsRange> range = aRange.AsDynamicRange();
-    range->RegisterSelection(*this);
-  }
+  aRange.RegisterSelection(*this);
+
   if (!mFrameSelection) {
     return;  // nothing to do
   }

dom/base/StaticRange.cpp

@@ -90,14 +90,25 @@ already_AddRefed<StaticRange> StaticRange::Create(
   return staticRange.forget();
 }
 
+StaticRange::~StaticRange() {
+  DoSetRange(RawRangeBoundary(), RawRangeBoundary(), nullptr);
+}
+
 template <typename SPT, typename SRT, typename EPT, typename ERT>
 void StaticRange::DoSetRange(const RangeBoundaryBase<SPT, SRT>& aStartBoundary,
                              const RangeBoundaryBase<EPT, ERT>& aEndBoundary,
                              nsINode* aRootNode) {
+  bool checkCommonAncestor =
+      IsInAnySelection() && (mStart.Container() != aStartBoundary.Container() ||
+                             mEnd.Container() != aEndBoundary.Container());
   mStart.CopyFrom(aStartBoundary, RangeBoundaryIsMutationObserved::No);
   mEnd.CopyFrom(aEndBoundary, RangeBoundaryIsMutationObserved::No);
   MOZ_ASSERT(mStart.IsSet() == mEnd.IsSet());
   mIsPositioned = mStart.IsSet() && mEnd.IsSet();
+
+  if (checkCommonAncestor) {
+    UpdateCommonAncestorIfNecessary();
+  }
 }
 
 /* static */

dom/base/StaticRange.h

@@ -75,7 +75,7 @@ class StaticRange final : public AbstractRange {
  protected:
   explicit StaticRange(nsINode* aNode)
       : AbstractRange(aNode, /* aIsDynamicRange = */ false) {}
-  virtual ~StaticRange() = default;
+  virtual ~StaticRange();
 
  public:
   NS_DECL_ISUPPORTS_INHERITED

dom/base/nsINode.cpp

@@ -345,12 +345,12 @@ bool nsINode::IsSelected(const uint32_t aStartOffset,
   nsTHashSet<Selection*> ancestorSelections;
   for (; n; n = GetClosestCommonInclusiveAncestorForRangeInSelection(
                 n->GetParentNode())) {
-    const LinkedList<nsRange>* ranges =
+    const LinkedList<AbstractRange>* ranges =
         n->GetExistingClosestCommonInclusiveAncestorRanges();
     if (!ranges) {
       continue;
     }
-    for (const nsRange* range : *ranges) {
+    for (const AbstractRange* range : *ranges) {
       MOZ_ASSERT(range->IsInAnySelection(),
                  "Why is this range registered with a node?");
       // Looks like that IsInSelection() assert fails sometimes...

dom/base/nsINode.h

@@ -76,6 +76,7 @@ inline bool IsSpaceCharacter(char aChar) {
   return aChar == ' ' || aChar == '\t' || aChar == '\n' || aChar == '\r' ||
          aChar == '\f';
 }
+class AbstractRange;
 class AccessibleNode;
 template <typename T>
 class AncestorsOfTypeIterator;
@@ -1350,7 +1351,7 @@ class nsINode : public mozilla::dom::EventTarget {
      * pushing DOMSlots up to the next allocation bucket size, at the cost of
      * some complexity.
      */
-    mozilla::UniquePtr<mozilla::LinkedList<nsRange>>
+    mozilla::UniquePtr<mozilla::LinkedList<mozilla::dom::AbstractRange>>
         mClosestCommonInclusiveAncestorRanges;
   };
 
@@ -2211,7 +2212,7 @@ class nsINode : public mozilla::dom::EventTarget {
   /**
    * See nsSlots::mClosestCommonInclusiveAncestorRanges.
    */
-  const mozilla::LinkedList<nsRange>*
+  const mozilla::LinkedList<mozilla::dom::AbstractRange>*
   GetExistingClosestCommonInclusiveAncestorRanges() const {
     if (!HasSlots()) {
       return nullptr;
@@ -2222,7 +2223,7 @@ class nsINode : public mozilla::dom::EventTarget {
   /**
    * See nsSlots::mClosestCommonInclusiveAncestorRanges.
    */
-  mozilla::LinkedList<nsRange>*
+  mozilla::LinkedList<mozilla::dom::AbstractRange>*
   GetExistingClosestCommonInclusiveAncestorRanges() {
     if (!HasSlots()) {
       return nullptr;
@@ -2233,7 +2234,7 @@ class nsINode : public mozilla::dom::EventTarget {
   /**
    * See nsSlots::mClosestCommonInclusiveAncestorRanges.
    */
-  mozilla::UniquePtr<mozilla::LinkedList<nsRange>>&
+  mozilla::UniquePtr<mozilla::LinkedList<mozilla::dom::AbstractRange>>&
   GetClosestCommonInclusiveAncestorRangesPtr() {
     return Slots()->mClosestCommonInclusiveAncestorRanges;
   }

dom/base/nsRange.cpp

@@ -166,7 +166,6 @@ nsRange::~nsRange() {
 
 nsRange::nsRange(nsINode* aNode)
     : AbstractRange(aNode, /* aIsDynamicRange = */ true),
-      mRegisteredClosestCommonInclusiveAncestor(nullptr),
       mNextStartRef(nullptr),
       mNextEndRef(nullptr) {
   // printf("Size of nsRange: %zu\n", sizeof(nsRange));
@@ -218,19 +217,8 @@ NS_INTERFACE_MAP_END_INHERITING(AbstractRange)
 NS_IMPL_CYCLE_COLLECTION_CLASS(nsRange)
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(nsRange, AbstractRange)
-  tmp->mSelections.Clear();
-  // We _could_ just rely on Reset() to
-  // UnregisterClosestCommonInclusiveAncestor(), but it wouldn't know we're
-  // calling it from Unlink and so would do more work than it really needs to.
-  if (tmp->mRegisteredClosestCommonInclusiveAncestor) {
-    tmp->UnregisterClosestCommonInclusiveAncestor(
-        tmp->mRegisteredClosestCommonInclusiveAncestor, true);
-  }
-
+  // `Reset()` unlinks `mStart`, `mEnd` and `mRoot`.
   tmp->Reset();
-
-  MOZ_DIAGNOSTIC_ASSERT(!tmp->isInList(),
-                        "Shouldn't be registered now that we're unlinking");
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(nsRange, AbstractRange)
@@ -246,103 +234,6 @@ bool nsRange::MaybeInterruptLastRelease() {
   return interrupt;
 }
 
-static void MarkDescendants(nsINode* aNode) {
-  // Set NodeIsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection on
-  // aNode's descendants unless aNode is already marked as a range common
-  // ancestor or a descendant of one, in which case all of our descendants have
-  // the bit set already.
-  if (!aNode->IsMaybeSelected()) {
-    // don't set the Descendant bit on |aNode| itself
-    nsINode* node = aNode->GetNextNode(aNode);
-    while (node) {
-      node->SetDescendantOfClosestCommonInclusiveAncestorForRangeInSelection();
-      if (!node->IsClosestCommonInclusiveAncestorForRangeInSelection()) {
-        node = node->GetNextNode(aNode);
-      } else {
-        // optimize: skip this sub-tree since it's marked already.
-        node = node->GetNextNonChildNode(aNode);
-      }
-    }
-  }
-}
-
-static void UnmarkDescendants(nsINode* aNode) {
-  // Unset NodeIsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection
-  // on aNode's descendants unless aNode is a descendant of another range common
-  // ancestor. Also, exclude descendants of range common ancestors (but not the
-  // common ancestor itself).
-  if (!aNode
-           ->IsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection()) {
-    // we know |aNode| doesn't have any bit set
-    nsINode* node = aNode->GetNextNode(aNode);
-    while (node) {
-      node->ClearDescendantOfClosestCommonInclusiveAncestorForRangeInSelection();
-      if (!node->IsClosestCommonInclusiveAncestorForRangeInSelection()) {
-        node = node->GetNextNode(aNode);
-      } else {
-        // We found an ancestor of an overlapping range, skip its descendants.
-        node = node->GetNextNonChildNode(aNode);
-      }
-    }
-  }
-}
-
-void nsRange::RegisterClosestCommonInclusiveAncestor(nsINode* aNode) {
-  MOZ_ASSERT(aNode, "bad arg");
-
-  MOZ_DIAGNOSTIC_ASSERT(IsInAnySelection(),
-                        "registering range not in selection");
-
-  mRegisteredClosestCommonInclusiveAncestor = aNode;
-
-  MarkDescendants(aNode);
-
-  UniquePtr<LinkedList<nsRange>>& ranges =
-      aNode->GetClosestCommonInclusiveAncestorRangesPtr();
-  if (!ranges) {
-    ranges = MakeUnique<LinkedList<nsRange>>();
-  }
-
-  MOZ_DIAGNOSTIC_ASSERT(!isInList());
-  ranges->insertBack(this);
-  aNode->SetClosestCommonInclusiveAncestorForRangeInSelection();
-}
-
-void nsRange::UnregisterClosestCommonInclusiveAncestor(nsINode* aNode,
-                                                       bool aIsUnlinking) {
-  MOZ_ASSERT(aNode, "bad arg");
-  NS_ASSERTION(aNode->IsClosestCommonInclusiveAncestorForRangeInSelection(),
-               "wrong node");
-  MOZ_DIAGNOSTIC_ASSERT(aNode == mRegisteredClosestCommonInclusiveAncestor,
-                        "wrong node");
-  LinkedList<nsRange>* ranges =
-      aNode->GetExistingClosestCommonInclusiveAncestorRanges();
-  MOZ_ASSERT(ranges);
-
-  mRegisteredClosestCommonInclusiveAncestor = nullptr;
-
-#ifdef DEBUG
-  bool found = false;
-  for (nsRange* range : *ranges) {
-    if (range == this) {
-      found = true;
-      break;
-    }
-  }
-  MOZ_ASSERT(found,
-             "We should be in the list on our registered common ancestor");
-#endif  // DEBUG
-
-  remove();
-
-  // We don't want to waste time unmarking flags on nodes that are
-  // being unlinked anyway.
-  if (!aIsUnlinking && ranges->isEmpty()) {
-    aNode->ClearClosestCommonInclusiveAncestorForRangeInSelection();
-    UnmarkDescendants(aNode);
-  }
-}
-
 void nsRange::AdjustNextRefsOnCharacterDataSplit(
     const nsIContent& aContent, const CharacterDataChangeInfo& aInfo) {
   // If the splitted text node is immediately before a range boundary point
@@ -594,7 +485,7 @@ void nsRange::ContentAppended(nsIContent* aFirstNewContent) {
     while (child) {
       if (!child
                ->IsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection()) {
-        MarkDescendants(child);
+        MarkDescendants(*child);
         child
             ->SetDescendantOfClosestCommonInclusiveAncestorForRangeInSelection();
       }
@@ -646,7 +537,7 @@ void nsRange::ContentInserted(nsIContent* aChild) {
   if (container->IsMaybeSelected() &&
       !aChild
            ->IsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection()) {
-    MarkDescendants(aChild);
+    MarkDescendants(*aChild);
     aChild->SetDescendantOfClosestCommonInclusiveAncestorForRangeInSelection();
   }
 
@@ -739,7 +630,7 @@ void nsRange::ContentRemoved(nsIContent* aChild, nsIContent* aPreviousSibling) {
           ->IsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection()) {
     aChild
         ->ClearDescendantOfClosestCommonInclusiveAncestorForRangeInSelection();
-    UnmarkDescendants(aChild);
+    UnmarkDescendants(*aChild);
   }
 }
 
@@ -985,26 +876,7 @@ void nsRange::DoSetRange(const RangeBoundaryBase<SPT, SRT>& aStartBoundary,
   mEnd.CopyFrom(aEndBoundary, RangeBoundaryIsMutationObserved::Yes);
 
   if (checkCommonAncestor) {
-    nsINode* oldCommonAncestor = mRegisteredClosestCommonInclusiveAncestor;
-    nsINode* newCommonAncestor = GetClosestCommonInclusiveAncestor();
-    if (newCommonAncestor != oldCommonAncestor) {
-      if (oldCommonAncestor) {
-        UnregisterClosestCommonInclusiveAncestor(oldCommonAncestor, false);
-      }
-      if (newCommonAncestor) {
-        RegisterClosestCommonInclusiveAncestor(newCommonAncestor);
-      } else {
-        MOZ_DIAGNOSTIC_ASSERT(!mIsPositioned, "unexpected disconnected nodes");
-        mSelections.Clear();
-        MOZ_DIAGNOSTIC_ASSERT(
-            !mRegisteredClosestCommonInclusiveAncestor,
-            "How can we have a registered common ancestor when we "
-            "didn't register ourselves?");
-        MOZ_DIAGNOSTIC_ASSERT(!isInList(),
-                              "Shouldn't be registered if we have no "
-                              "mRegisteredClosestCommonInclusiveAncestor");
-      }
-    }
+    UpdateCommonAncestorIfNecessary();
   }
 
   // This needs to be the last thing this function does, other than notifying
@@ -1034,43 +906,6 @@ void nsRange::DoSetRange(const RangeBoundaryBase<SPT, SRT>& aStartBoundary,
   }
 }
 
-bool nsRange::IsInSelection(const Selection& aSelection) const {
-  return mSelections.Contains(&aSelection);
-}
-
-void nsRange::RegisterSelection(Selection& aSelection) {
-  if (IsInSelection(aSelection)) {
-    return;
-  }
-  bool isFirstSelection = mSelections.IsEmpty();
-  mSelections.AppendElement(&aSelection);
-  if (isFirstSelection && !mRegisteredClosestCommonInclusiveAncestor) {
-    nsINode* commonAncestor = GetClosestCommonInclusiveAncestor();
-    MOZ_ASSERT(commonAncestor, "unexpected disconnected nodes");
-    RegisterClosestCommonInclusiveAncestor(commonAncestor);
-  }
-}
-
-const nsTArray<WeakPtr<Selection>>& nsRange::GetSelections() const {
-  return mSelections;
-}
-
-void nsRange::UnregisterSelection(Selection& aSelection) {
-  mSelections.RemoveElement(&aSelection);
-  if (mSelections.IsEmpty() && mRegisteredClosestCommonInclusiveAncestor) {
-    UnregisterClosestCommonInclusiveAncestor(
-        mRegisteredClosestCommonInclusiveAncestor, false);
-    MOZ_DIAGNOSTIC_ASSERT(
-        !mRegisteredClosestCommonInclusiveAncestor,
-        "How can we have a registered common ancestor when we "
-        "just unregistered?");
-    MOZ_DIAGNOSTIC_ASSERT(
-        !isInList(),
-        "Shouldn't be registered if we have no "
-        "mRegisteredClosestCommonInclusiveAncestor after unregistering");
-  }
-}
-
 void nsRange::Reset() {
   DoSetRange(RawRangeBoundary(), RawRangeBoundary(), nullptr);
 }

dom/base/nsRange.h

@@ -20,7 +20,6 @@
 #include "mozilla/ErrorResult.h"
 #include "mozilla/RangeBoundary.h"
 #include "mozilla/RefPtr.h"
-#include "mozilla/WeakPtr.h"
 
 namespace mozilla {
 class RectCallback;
@@ -36,9 +35,7 @@ class Selection;
 }  // namespace mozilla
 
 class nsRange final : public mozilla::dom::AbstractRange,
-                      public nsStubMutationObserver,
-                      // For linking together selection-associated ranges.
-                      public mozilla::LinkedListElement<nsRange> {
+                      public nsStubMutationObserver {
   using ErrorResult = mozilla::ErrorResult;
   using AbstractRange = mozilla::dom::AbstractRange;
   using DocGroup = mozilla::dom::DocGroup;
@@ -91,28 +88,6 @@ class nsRange final : public mozilla::dom::AbstractRange,
 
   nsINode* GetRoot() const { return mRoot; }
 
-  /**
-   * Return true if this range is part of a Selection object
-   * and isn't detached.
-   */
-  bool IsInAnySelection() const { return !mSelections.IsEmpty(); }
-
-  MOZ_CAN_RUN_SCRIPT void RegisterSelection(
-      mozilla::dom::Selection& aSelection);
-
-  void UnregisterSelection(mozilla::dom::Selection& aSelection);
-
-  /**
-   * Returns a list of all Selections the range is associated with.
-   */
-  const nsTArray<mozilla::WeakPtr<mozilla::dom::Selection>>& GetSelections()
-      const;
-
-  /**
-   * Return true if this range is in |aSelection|.
-   */
-  bool IsInSelection(const mozilla::dom::Selection& aSelection) const;
-
   /**
    * Return true if this range was generated.
    * @see SetIsGenerated
@@ -377,16 +352,6 @@ class nsRange final : public mozilla::dom::AbstractRange,
   nsINode* GetRegisteredClosestCommonInclusiveAncestor();
 
  protected:
-  /**
-   * https://dom.spec.whatwg.org/#concept-tree-inclusive-ancestor
-   */
-  void RegisterClosestCommonInclusiveAncestor(nsINode* aNode);
-  /**
-   * https://dom.spec.whatwg.org/#concept-tree-inclusive-ancestor
-   */
-  void UnregisterClosestCommonInclusiveAncestor(nsINode* aNode,
-                                                bool aIsUnlinking);
-
   /**
    * DoSetRange() is called when `AbstractRange::SetStartAndEndInternal()` sets
    * mStart and mEnd, or some other internal methods modify `mStart` and/or
@@ -448,13 +413,6 @@ class nsRange final : public mozilla::dom::AbstractRange,
 #endif  // #ifdef DEBUG
 
   nsCOMPtr<nsINode> mRoot;
-  // mRegisteredClosestCommonInclusiveAncestor is only non-null when the range
-  // IsInAnySelection().  It's kept alive via mStart/mEnd,
-  // because we update it any time those could become disconnected from it.
-  nsINode* MOZ_NON_OWNING_REF mRegisteredClosestCommonInclusiveAncestor;
-
-  // A Range can be part of multiple |Selection|s. This is a very rare use case.
-  AutoTArray<mozilla::WeakPtr<mozilla::dom::Selection>, 1> mSelections;
 
   // These raw pointers are used to remember a child that is about
   // to be inserted between a CharacterData call and a subsequent

dom/base/nsTextNode.cpp

@@ -133,15 +133,9 @@ void nsTextNode::List(FILE* out, int32_t aIndent) const {
   fprintf(out, "Text@%p", static_cast<const void*>(this));
   fprintf(out, " flags=[%08x]", static_cast<unsigned int>(GetFlags()));
   if (IsClosestCommonInclusiveAncestorForRangeInSelection()) {
-    const LinkedList<nsRange>* ranges =
+    const LinkedList<AbstractRange>* ranges =
         GetExistingClosestCommonInclusiveAncestorRanges();
-    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;
-      }
-    }
+    uint32_t count = ranges ? ranges->length() : 0;
     fprintf(out, " ranges:%d", count);
   }
   fprintf(out, " primaryframe=%p", static_cast<void*>(GetPrimaryFrame()));

testing/web-platform/meta/css/css-highlight-api/painting/custom-highlight-painting-staticrange-002.html.ini

@@ -1,2 +0,0 @@
-[custom-highlight-painting-staticrange-002.html]
-  expected: FAIL

testing/web-platform/meta/css/css-highlight-api/painting/custom-highlight-painting-staticrange-003.html.ini

@@ -1,2 +0,0 @@
-[custom-highlight-painting-staticrange-003.html]
-  expected: FAIL