Remove the concept of user stylesheets.

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 276 matching lines @@
     // FIXME: This should probably go away, folded into FontBuilder.
     void updateFont(StyleResolverState&);
 
     void collectPseudoRulesForElement(Element*, ElementRuleCollector&, PseudoId, unsigned rulesToInclude);
     void matchUARules(ElementRuleCollector&, RuleSet*);
     void matchAuthorRules(Element*, ElementRuleCollector&, bool includeEmptyRules);
     void matchAuthorRulesForShadowHost(Element*, ElementRuleCollector&, bool includeEmptyRules, Vector<ScopedStyleResolver*, 8>& resolvers, Vector<ScopedStyleResolver*, 8>& resolversInShadowTree);
     void matchHostRules(Element*, ScopedStyleResolver*, ElementRuleCollector&, bool includeEmptyRules);
     void matchAllRules(StyleResolverState&, ElementRuleCollector&, bool matchAuthorAndUserStyles, bool includeSMILProperties);
     void matchUARules(ElementRuleCollector&);
-    void matchUserRules(ElementRuleCollector&, bool includeEmptyRules);
     void collectFeatures();
     void collectTreeBoundaryCrossingRules(ElementRuleCollector&, bool includeEmptyRules);
 
     bool fastRejectSelector(const RuleData&) const;
 
     void applyMatchedProperties(StyleResolverState&, const MatchResult&, Element* animatingElement);
 
     enum StyleApplicationPass {
         VariableDefinitions,
         AnimationProperties,
@@ skipping 74 matching lines @@
         PseudoId ignoreDynamicPseudo = NOPSEUDO;
         if (selectorChecker.match(selectorCheckingContext, ignoreDynamicPseudo, DOMSiblingTraversalStrategy()) == SelectorChecker::SelectorMatches)
             return true;
     }
     return false;
 }
 
 } // namespace WebCore
 
 #endif // StyleResolver_h