Oilpan: tidy StylePropertySerializer's handling of GCed objects.

Source/core/css/StylePropertySerializer.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Research In Motion Limited. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. 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 16 matching lines @@
 #include "core/css/StylePropertySet.h"
 
 #include "wtf/BitArray.h"
 
 namespace blink {
 
 class StylePropertySet;
 class StylePropertyShorthand;
 
 class StylePropertySerializer {
+    STACK_ALLOCATED();
 public:
     explicit StylePropertySerializer(const StylePropertySet&);
 
     String asText() const;
     String getPropertyValue(CSSPropertyID) const;
 private:
     String getCommonValue(const StylePropertyShorthand&) const;
     enum CommonValueMode { OmitUncommonValues, ReturnNullOnUncommonValues };
     String borderPropertyValue(CommonValueMode) const;
     String getLayeredShorthandValue(const StylePropertyShorthand&) const;
@@ skipping 34 matching lines @@
         bool isValid() const { return m_value; }
 
     private:
         RawPtrWillBeMember<const CSSValue> m_value;
         CSSPropertyID m_id;
         bool m_isImportant;
         bool m_isImplicit;
         bool m_isInherited;
     };
 
-    class StylePropertySetForSerializer {
+    class StylePropertySetForSerializer final {
+        DISALLOW_ALLOCATION();
     public:
         explicit StylePropertySetForSerializer(const StylePropertySet&);
 
         unsigned propertyCount() const;
         PropertyValueForSerializer propertyAt(unsigned index) const;
         bool shouldProcessPropertyAt(unsigned index) const;
         int findPropertyIndex(CSSPropertyID) const;
         const CSSValue* getPropertyCSSValue(CSSPropertyID) const;
         String getPropertyValue(CSSPropertyID) const;
         bool isPropertyImplicit(CSSPropertyID) const;
         bool propertyIsImportant(CSSPropertyID) const;
 
+        DECLARE_TRACE();
+
     private:
         bool hasExpandedAllProperty() const { return hasAllProperty() && m_needToExpandAll; }
         bool hasAllProperty() const { return m_allIndex != -1; }
 
-        const StylePropertySet& m_propertySet;
+        RawPtrWillBeMember<const StylePropertySet> m_propertySet;
         int m_allIndex;
         BitArray<numCSSProperties> m_longhandPropertyUsed;
         bool m_needToExpandAll;
     };
 
     const StylePropertySetForSerializer m_propertySet;
 };
 
 } // namespace blink
 
-#endif
+#endif // StylePropertySerializer_h