Make event.composedPath() on window behave the same way as that on document

third_party/WebKit/Source/core/events/EventPath.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 55 matching lines @@
     return *m_windowEventContext;
   }
   void ensureWindowEventContext();
 
   bool isEmpty() const { return m_nodeEventContexts.isEmpty(); }
   size_t size() const { return m_nodeEventContexts.size(); }
 
   void adjustForRelatedTarget(Node&, EventTarget* relatedTarget);
   void adjustForTouchEvent(TouchEvent&);
 
+  NodeEventContext& topNodeEventContext();
+
   static EventTarget* eventTargetRespectingTargetRules(Node&);
 
   DECLARE_TRACE();
   void clear() {
     m_nodeEventContexts.clear();
     m_treeScopeEventContexts.clear();
   }
 
  private:
   EventPath();
@@ skipping 24 matching lines @@
 
   using RelatedTargetMap = HeapHashMap<Member<TreeScope>, Member<EventTarget>>;
 
   static void buildRelatedNodeMap(const Node&, RelatedTargetMap&);
   static EventTarget* findRelatedNode(TreeScope&, RelatedTargetMap&);
 
 #if DCHECK_IS_ON()
   static void checkReachability(TreeScope&, TouchList&);
 #endif
 
-  const NodeEventContext& topNodeEventContext();
-
   HeapVector<NodeEventContext> m_nodeEventContexts;
   Member<Node> m_node;
   Member<Event> m_event;
   HeapVector<Member<TreeScopeEventContext>> m_treeScopeEventContexts;
   Member<WindowEventContext> m_windowEventContext;
 };
 
 }  // namespace blink
 
 #endif