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

Source/core/css/resolver/StyleResolver.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 194 matching lines @@
     void printStats();
 
     unsigned accessCount() const { return m_accessCount; }
     void didAccess() { ++m_accessCount; }
 
     void increaseStyleSharingDepth() { ++m_styleSharingDepth; }
     void decreaseStyleSharingDepth() { --m_styleSharingDepth; }
 
     PassRefPtrWillBeRawPtr<PseudoElement> createPseudoElementIfNeeded(Element& parent, PseudoId);
 
-    void trace(Visitor*);
+    virtual void trace(Visitor*);
 
 private:
     void initWatchedSelectorRules(const WillBeHeapVector<RefPtrWillBeMember<StyleRule> >& watchedSelectors);
 
     // FIXME: This should probably go away, folded into FontBuilder.
     void updateFont(StyleResolverState&);
 
     void loadPendingResources(StyleResolverState&);
     void adjustRenderStyle(StyleResolverState&, Element*);
 
@@ skipping 89 matching lines @@
     OwnPtr<StyleResolverStats> m_styleResolverStatsTotals;
     unsigned m_styleResolverStatsSequence;
 
     // Use only for Internals::updateStyleAndReturnAffectedElementCount.
     unsigned m_accessCount;
 };
 
 } // namespace blink
 
 #endif // StyleResolver_h