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

Source/core/html/HTMLLinkElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * 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.
@@ skipping 177 matching lines @@
     virtual void finishParsingChildren() OVERRIDE;
 
     // From LinkLoaderClient
     virtual void linkLoaded() OVERRIDE;
     virtual void linkLoadingErrored() OVERRIDE;
     virtual void didStartLinkPrerender() OVERRIDE;
     virtual void didStopLinkPrerender() OVERRIDE;
     virtual void didSendLoadForLinkPrerender() OVERRIDE;
     virtual void didSendDOMContentLoadedForLinkPrerender() OVERRIDE;
 
+    virtual void trace(Visitor*) OVERRIDE;
+
 private:
     HTMLLinkElement(Document&, bool createdByParser);
 
     OwnPtr<LinkResource> m_link;
     LinkLoader m_linkLoader;
 
     String m_type;
     String m_media;
-    RefPtr<DOMSettableTokenList> m_sizes;
+    RefPtrWillBeMember<DOMSettableTokenList> m_sizes;
     Vector<IntSize> m_iconSizes;
     LinkRelAttribute m_relAttribute;
 
     bool m_createdByParser;
     bool m_isInShadowTree;
 };
 
 } //namespace
 
 #endif