Factor the style invalidation tree walk out of RuleFeatureSet, and make it generic.

Source/core/css/RuleFeature.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 58 matching lines @@
     inline bool hasSelectorForAttribute(const AtomicString& attributeName) const
     {
         ASSERT(!attributeName.isEmpty());
         return m_metadata.attrsInRules.contains(attributeName);
     }
 
     inline bool hasSelectorForClass(const AtomicString& classValue) const
     {
         ASSERT(!classValue.isEmpty());
         return m_classInvalidationSets.get(classValue);
-
     }
 
     inline bool hasSelectorForId(const AtomicString& idValue) const
     {
         return m_metadata.idsInRules.contains(idValue);
     }
 
     void scheduleStyleInvalidationForClassChange(const SpaceSplitString& changedClasses, Element*);
     void scheduleStyleInvalidationForClassChange(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses, Element*);
 
@@ skipping 43 matching lines @@
     static InvalidationSetMode supportsClassDescendantInvalidation(const CSSSelector&);
 
     void collectFeaturesFromSelector(const CSSSelector&, FeatureMetadata&, InvalidationSetMode);
     void collectFeaturesFromSelectorList(const CSSSelectorList*, FeatureMetadata&, InvalidationSetMode);
 
     DescendantInvalidationSet& ensureClassInvalidationSet(const AtomicString& className);
     InvalidationSetMode updateClassInvalidationSets(const CSSSelector&);
 
     void addClassToInvalidationSet(const AtomicString& className, Element*);
 
-    bool invalidateStyleForClassChange(Element*, Vector<AtomicString>&, bool foundInvalidationSet);
-    bool invalidateStyleForClassChangeOnChildren(Element*, Vector<AtomicString>& invalidationClasses, bool foundInvalidationSet);
-
     InvalidationList& ensurePendingInvalidationList(Element*);
 
     FeatureMetadata m_metadata;
     InvalidationSetMap m_classInvalidationSets;
     PendingInvalidationMap m_pendingInvalidationMap;
 
     bool m_targetedStyleRecalcEnabled;
+
+    friend class StyleInvalidationTreeWalk;
 };
 
+
 } // namespace WebCore
 
 #endif // RuleFeature_h