Let StyleResolver figure out differences between UA style and resolved style.

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 16 matching lines @@
 #include "core/css/RuleFeature.h"
 #include "core/css/RuleSet.h"
 #include "core/css/SelectorChecker.h"
 #include "core/css/SelectorFilter.h"
 #include "core/css/SiblingTraversalStrategies.h"
 #include "core/css/TreeBoundaryCrossingRules.h"
 #include "core/css/resolver/CSSPropertyPriority.h"
 #include "core/css/resolver/MatchedPropertiesCache.h"
 #include "core/css/resolver/StyleBuilder.h"
 #include "core/css/resolver/StyleResourceLoader.h"
+#include "core/layout/style/AuthorStyleInfo.h"
+#include "core/layout/style/CachedUAStyle.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Deque.h"
 #include "wtf/HashMap.h"
 #include "wtf/HashSet.h"
 #include "wtf/ListHashSet.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
@@ skipping 240 matching lines @@
     OwnPtr<StyleResolverStats> m_styleResolverStatsTotals;
     unsigned m_styleResolverStatsSequence;
 
     // Use only for Internals::updateStyleAndReturnAffectedElementCount.
     unsigned m_accessCount;
 };
 
 } // namespace blink
 
 #endif // StyleResolver_h