Hollow out more of the tracing system in oilpan

sky/engine/core/css/FontFace.h

 /*
  * Copyright (C) 2013 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 76 matching lines @@
 
     ScriptPromise load(ScriptState*);
 
     LoadStatus loadStatus() const { return m_status; }
     void setLoadStatus(LoadStatus);
     void setError(PassRefPtr<DOMException> = nullptr);
     DOMException* error() const { return m_error.get(); }
     FontTraits traits() const;
     CSSFontFace* cssFontFace() { return m_cssFontFace.get(); }
 
-    void trace(Visitor*);
-
     bool hadBlankText() const;
 
     class LoadFontCallback : public RefCounted<LoadFontCallback> {
     public:
         virtual ~LoadFontCallback() { }
         virtual void notifyLoaded(FontFace*) = 0;
         virtual void notifyError(FontFace*) = 0;
-        virtual void trace(Visitor*) { }
     };
     void loadWithCallback(PassRefPtr<LoadFontCallback>, ExecutionContext*);
 
 private:
     FontFace();
     FontFace(ExecutionContext*, const AtomicString& family, const Dictionary& descriptors);
 
     void initCSSFontFace(Document*, PassRefPtr<CSSValue> src);
     void initCSSFontFace(const unsigned char* data, unsigned size);
     void setPropertyFromString(const Document*, const String&, CSSPropertyID, ExceptionState* = 0);
@@ skipping 19 matching lines @@
     Persistent<LoadedProperty> m_loadedProperty;
     OwnPtr<CSSFontFace> m_cssFontFace;
     Vector<RefPtr<LoadFontCallback> > m_callbacks;
 };
 
 typedef Vector<RefPtr<FontFace> > FontFaceArray;
 
 } // namespace blink
 
 #endif // FontFace_h