Oilpan: Move CSSStyleDeclaration and subclasses to the heap using transistion types.

Source/core/css/CSSKeyframeRule.h

 /*
  * Copyright (C) 2007, 2008, 2012 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 67 matching lines @@
 
     virtual CSSRule::Type type() const OVERRIDE { return KEYFRAME_RULE; }
     virtual String cssText() const OVERRIDE { return m_keyframe->cssText(); }
     virtual void reattach(StyleRuleBase*) OVERRIDE;
 
     String keyText() const { return m_keyframe->keyText(); }
     void setKeyText(const String& s) { m_keyframe->setKeyText(s); }
 
     CSSStyleDeclaration* style() const;
 
-    virtual void trace(Visitor* visitor) OVERRIDE { CSSRule::trace(visitor); }
+    virtual void trace(Visitor*) OVERRIDE;
 
 private:
     CSSKeyframeRule(StyleKeyframe*, CSSKeyframesRule* parent);
 
     RefPtr<StyleKeyframe> m_keyframe;
-    mutable RefPtr<StyleRuleCSSStyleDeclaration> m_propertiesCSSOMWrapper;
+    mutable RefPtrWillBeMember<StyleRuleCSSStyleDeclaration> m_propertiesCSSOMWrapper;
 
     friend class CSSKeyframesRule;
 };
 
 DEFINE_CSS_RULE_TYPE_CASTS(CSSKeyframeRule, KEYFRAME_RULE);
 
 } // namespace WebCore
 
 #endif // CSSKeyframeRule_h