Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/testing/LayerRect.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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 40 matching lines @@
     }
 
     Node* layerAssociatedNode() const { return m_layerAssociatedNode.get(); }
     String layerType() const { return m_layerType; }
     int associatedNodeOffsetX() const { return m_associatedNodeOffsetX; }
     int associatedNodeOffsetY() const { return m_associatedNodeOffsetY; }
     ClientRect* layerRelativeRect() const { return m_rect.get(); }
 
     void trace(Visitor* visitor)
     {
+        visitor->trace(m_layerAssociatedNode);
         visitor->trace(m_rect);
     }
 
 private:
     LayerRect(PassRefPtr<Node> node, const String& layerName, int nodeOffsetX, int nodeOffsetY, PassRefPtrWillBeRawPtr<ClientRect> rect)
         : m_layerAssociatedNode(node)
         , m_layerType(layerName)
         , m_associatedNodeOffsetX(nodeOffsetX)
         , m_associatedNodeOffsetY(nodeOffsetY)
         , m_rect(rect)
     {
     }
 
-    RefPtr<Node> m_layerAssociatedNode;
+    RefPtrWillBeMember<Node> m_layerAssociatedNode;
     String m_layerType;
     int m_associatedNodeOffsetX;
     int m_associatedNodeOffsetY;
     RefPtrWillBeMember<ClientRect> m_rect;
 };
 
 } // namespace WebCore
 
 #endif