Avoid style sharing with mis-matched descendant selectors

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 335 matching lines @@
     RefPtr<CSSFontSelector> m_fontSelector;
 
     RefPtr<ViewportStyleResolver> m_viewportStyleResolver;
 
     ScopedStyleTree m_styleTree;
 
     // FIXME: The entire logic of collecting features on StyleResolver, as well astransferring them
     // between various parts of machinery smells wrong. This needs to be better somehow.
     RuleFeatureSet m_features;
     OwnPtr<RuleSet> m_siblingRuleSet;
+    OwnPtr<RuleSet> m_descendantRuleSet;
     OwnPtr<RuleSet> m_uncommonAttributeRuleSet;
 
     InspectorCSSOMWrappers m_inspectorCSSOMWrappers;
 
     StyleResourceLoader m_styleResourceLoader;
 
     StyleSharingList m_styleSharingList;
 
 #ifdef STYLE_STATS
     static StyleSharingStats m_styleSharingStats;
@@ skipping 11 matching lines @@
         PseudoId ignoreDynamicPseudo = NOPSEUDO;
         if (selectorChecker.match(selectorCheckingContext, ignoreDynamicPseudo, DOMSiblingTraversalStrategy()) == SelectorChecker::SelectorMatches)
             return true;
     }
     return false;
 }
 
 } // namespace WebCore
 
 #endif // StyleResolver_h