Make SelectorChecker a const operation over element.

sky/engine/core/css/ElementRuleCollector.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 79 matching lines @@
 // Create one, ask what rules the ElementResolveContext matches
 // and then let it go out of scope.
 // FIXME: Currently it modifies the RenderStyle but should not!
 class ElementRuleCollector {
     STACK_ALLOCATED();
     WTF_MAKE_NONCOPYABLE(ElementRuleCollector);
 public:
     ElementRuleCollector(const ElementResolveContext&, RenderStyle* = 0);
     ~ElementRuleCollector();
 
-    void setMode(SelectorChecker::Mode mode) { m_mode = mode; }
-
     void setMatchingUARules(bool matchingUARules) { m_matchingUARules = matchingUARules; }
 
     MatchResult& matchedResult();
 
     void collectMatchingRules(const MatchRequest&, RuleRange&, CascadeScope = ignoreCascadeScope, CascadeOrder = ignoreCascadeOrder);
     void sortAndTransferMatchedRules();
     void clearMatchedRules();
     void addElementStyleProperties(const StylePropertySet*, bool isCacheable = true);
 
 private:
@@ skipping 11 matching lines @@
 
     bool ruleMatches(const RuleData&, const ContainerNode* scope);
 
     void sortMatchedRules();
     void addMatchedRule(const RuleData*, CascadeScope, CascadeOrder, unsigned styleSheetIndex, const CSSStyleSheet* parentStyleSheet);
 
 private:
     const ElementResolveContext& m_context;
     RefPtr<RenderStyle> m_style; // FIXME: This can be mutated during matching!
 
-    SelectorChecker::Mode m_mode;
     bool m_matchingUARules;
 
     OwnPtr<Vector<MatchedRule, 32> > m_matchedRules;
 
     // Output.
     MatchResult m_result;
 };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_CSS_ELEMENTRULECOLLECTOR_H_