Oilpan: move DOM string collection objects to the Oilpan heap.

Source/core/dom/ElementRareData.cpp

 /*
  * Copyright (C) 2012 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 32 matching lines @@
     OwnPtrWillBePersistent<ActiveAnimations> m_activeAnimations;
 };
 
 CSSStyleDeclaration& ElementRareData::ensureInlineCSSStyleDeclaration(Element* ownerElement)
 {
     if (!m_cssomWrapper)
         m_cssomWrapper = adoptPtr(new InlineCSSStyleDeclaration(ownerElement));
     return *m_cssomWrapper;
 }
 
+void ElementRareData::trace(Visitor* visitor)
+{
+    visitor->trace(m_dataset);
+    visitor->trace(m_classList);
+}
 
 COMPILE_ASSERT(sizeof(ElementRareData) == sizeof(SameSizeAsElementRareData), ElementRareDataShouldStaySmall);
 
 } // namespace WebCore