[WIP] Use the flat tree for hover handling.

third_party/WebKit/Source/core/input/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 1455 matching lines @@
   // work that cleans the hover state.  Because the hover state for the main
   // frame is updated by calling Document::updateHoverActiveState
   while (newHoverFrameInDocument && newHoverFrameInDocument != m_frame) {
     newHoverFrameChain.push_back(newHoverFrameInDocument);
     Frame* parentFrame = newHoverFrameInDocument->tree().parent();
     newHoverFrameInDocument = parentFrame && parentFrame->isLocalFrame()
                                   ? toLocalFrame(parentFrame)
                                   : nullptr;
   }
 
-  Node* oldHoverNodeInCurDoc = m_frame->document()->hoverNode();
+  Node* oldHoverNodeInCurDoc = m_frame->document()->hoverElement();
   Node* newInnermostHoverNode = innerElement;
 
   if (newInnermostHoverNode != oldHoverNodeInCurDoc) {
     size_t indexFrameChain = newHoverFrameChain.size();
 
     // Clear the hover state on any frames which are no longer in the frame
     // chain of the hovered element.
     while (oldHoverNodeInCurDoc &&
            oldHoverNodeInCurDoc->isFrameOwnerElement()) {
       LocalFrame* newHoverFrame = nullptr;
       // If we can't get the frame from the new hover frame chain,
       // the newHoverFrame will be null and the old hover state will be cleared.
       if (indexFrameChain > 0)
         newHoverFrame = newHoverFrameChain[--indexFrameChain];
 
       HTMLFrameOwnerElement* owner =
           toHTMLFrameOwnerElement(oldHoverNodeInCurDoc);
       if (!owner->contentFrame() || !owner->contentFrame()->isLocalFrame())
         break;
 
       LocalFrame* oldHoverFrame = toLocalFrame(owner->contentFrame());
       Document* doc = oldHoverFrame->document();
       if (!doc)
         break;
 
-      oldHoverNodeInCurDoc = doc->hoverNode();
+      oldHoverNodeInCurDoc = doc->hoverElement();
       // If the old hovered frame is different from the new hovered frame.
       // we should clear the old hovered node from the old hovered frame.
       if (newHoverFrame != oldHoverFrame)
         doc->updateHoverActiveState(request, nullptr, nullptr);
     }
   }
 
   // Recursively set the new active/hover states on every frame in the chain of
   // innerElement.
   m_frame->document()->updateHoverActiveState(request, innerElement, nullptr);
@@ skipping 573 matching lines @@
     MouseEventWithHitTestResults& mev,
     LocalFrame* subframe) {
   WebInputEventResult result =
       subframe->eventHandler().handleMouseReleaseEvent(mev.event());
   if (result != WebInputEventResult::NotHandled)
     return result;
   return WebInputEventResult::HandledSystem;
 }
 
 }  // namespace blink