Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 3263 matching lines @@
         || isHTMLEmbedElement(*this)
         || isHTMLObjectElement(*this)
         || isHTMLAppletElement(*this)
         || isHTMLCanvasElement(*this))
         return false;
     if (FullscreenElementStack::isActiveFullScreenElement(this))
         return false;
     return true;
 }
 
+void Element::trace(Visitor* visitor)
+{
+    // FIXME: Oilpan: Perform this tracing directly on the element
+    // rare data once that is in the heap.
+    if (hasRareData())
+        elementRareData()->trace(visitor);
+    ContainerNode::trace(visitor);
+}
+
 } // namespace WebCore