1 files changed, 8 insertions, 3 deletions

diff --git a/chromium/third_party/blink/renderer/core/html/html_slot_element.h b/chromium/third_party/blink/renderer/core/html/html_slot_element.h
index 4e127e195c6..bec406ad9ed 100644
--- a/chromium/third_party/blink/renderer/core/html/html_slot_element.h
+++ b/chromium/third_party/blink/renderer/core/html/html_slot_element.h
@@ -64,13 +64,18 @@ class CORE_EXPORT HTMLSlotElement final : public HTMLElement {
     return nodes.IsEmpty() ? nullptr : nodes.back().Get();
   }
 
+  Node* AssignedNodeNextTo(const Node&) const;
+  Node* AssignedNodePreviousTo(const Node&) const;
+
   void AppendAssignedNode(Node&);
+  void ClearAssignedNodes();
 
   const HeapVector<Member<Node>> FlattenedAssignedNodes();
 
   void WillRecalcAssignedNodes() { ClearAssignedNodes(); }
   void DidRecalcAssignedNodes() {
-    UpdateFlatTreeNodeDataForAssignedNodes();
+    if (RuntimeEnabledFeatures::FastFlatTreeTraversalEnabled())
+      UpdateFlatTreeNodeDataForAssignedNodes();
     RecalcFlatTreeChildren();
   }
 
@@ -112,7 +117,7 @@ class CORE_EXPORT HTMLSlotElement final : public HTMLElement {
     return assigned_nodes_candidates_;
   }
 
-  void Trace(blink::Visitor*) override;
+  void Trace(Visitor*) override;
 
  private:
   InsertionNotificationRequest InsertedInto(ContainerNode&) final;
@@ -137,10 +142,10 @@ class CORE_EXPORT HTMLSlotElement final : public HTMLElement {
 
   void RecalcFlatTreeChildren();
   void UpdateFlatTreeNodeDataForAssignedNodes();
-  void ClearAssignedNodes();
   void ClearAssignedNodesAndFlatTreeChildren();
 
   HeapVector<Member<Node>> assigned_nodes_;
+  HeapHashMap<Member<const Node>, unsigned> assigned_nodes_index_;
   HeapVector<Member<Node>> flat_tree_children_;
 
   bool slotchange_event_enqueued_ = false;