Reduced the callers to the non-const version of CSSValueList::item()

third_party/WebKit/Source/core/frame/FrameSerializer.h

 /*
  * Copyright (C) 2011 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 110 matching lines @@
     // Serializes the css rule (including any imported stylesheets), adding referenced resources.
     void serializeCSSRule(CSSRule*);
 
     bool shouldAddURL(const KURL&);
 
     void addToResources(const Resource&, PassRefPtr<SharedBuffer>, const KURL&);
     void addImageToResources(ImageResource*, const KURL&);
     void addFontToResources(FontResource*);
 
     void retrieveResourcesForProperties(const StylePropertySet*, Document&);
-    void retrieveResourcesForCSSValue(CSSValue*, Document&);
+    void retrieveResourcesForCSSValue(const CSSValue*, Document&);
 
     Vector<SerializedResource>* m_resources;
     HashSet<KURL> m_resourceURLs;
 
     Delegate& m_delegate;
 };
 
 } // namespace blink
 
 #endif // FrameSerializer_h