Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/ElementRareData.h

 /*
  * Copyright (C) 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 David Smith <catfish.man@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 101 matching lines @@
             m_inputMethodContext = InputMethodContext::create(element);
         return *m_inputMethodContext;
     }
 
     bool hasPseudoElements() const;
     void clearPseudoElements();
 
     void setCustomElementDefinition(PassRefPtr<CustomElementDefinition> definition) { m_customElementDefinition = definition; }
     CustomElementDefinition* customElementDefinition() const { return m_customElementDefinition.get(); }
 
+    void trace(Visitor* visitor)
+    {
+        // FIXME: Oilpan: Implement real tracing of the
+        // ElementRareData when it has been moved to the
+        // oilpan heap and move the ElementShadow tracing
+        // to the ElementShadow when that has been moved
+        // to the oilpan heap.
+        visitor->trace(m_shadow);
+    }
+
 private:
     short m_tabindex;
 
     IntSize m_savedLayerScrollOffset;
 
     OwnPtr<DatasetDOMStringMap> m_dataset;
     OwnPtr<ClassList> m_classList;
     OwnPtr<ElementShadow> m_shadow;
     OwnPtr<NamedNodeMap> m_attributeMap;
     OwnPtr<InputMethodContext> m_inputMethodContext;
@@ skipping 74 matching lines @@
 }
 
 inline void ElementRareData::resetStyleState()
 {
     clearElementFlag(StyleAffectedByEmpty);
 }
 
 } // namespace
 
 #endif // ElementRareData_h