Oilpan: Ensure that classes with virtual trace methods always have vtables for their left-most base…

Source/core/svg/SVGViewSpec.h

 /*
  * Copyright (C) 2007 Rob Buis <buis@kde.org>
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 39 matching lines @@
     PassRefPtr<SVGTransformListTearOff> transformFromJavascript() { return m_transform ? m_transform->baseVal() : 0; }
     SVGElement* viewTarget() const;
     String viewBoxString() const;
     String preserveAspectRatioString() const;
     String transformString() const;
     String viewTargetString() const { return m_viewTargetString; }
     // override SVGZoomAndPan.setZoomAndPan so can throw exception on write
     void setZoomAndPan(unsigned short value) { } // read only
     void setZoomAndPan(unsigned short value, ExceptionState&);
 
-    void trace(Visitor*);
+    virtual void trace(Visitor*);
 
     SVGSVGElement* contextElement() { return m_contextElement.get(); }
 
 private:
     explicit SVGViewSpec(SVGSVGElement*);
 
     template<typename CharType>
     bool parseViewSpecInternal(const CharType* ptr, const CharType* end);
 
     RawPtrWillBeMember<SVGSVGElement> m_contextElement;
     RefPtr<SVGAnimatedTransformList> m_transform;
     String m_viewTargetString;
 };
 
 } // namespace blink
 
 #endif