Avoid style sharing with mis-matched descendant selectors

Source/core/css/resolver/ScopedStyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 378 matching lines @@
 }
 
 void ScopedStyleResolver::matchAuthorRules(ElementRuleCollector& collector, bool includeEmptyRules, bool applyAuthorStyles)
 {
     collector.clearMatchedRules();
     collector.matchedResult().ranges.lastAuthorRule = collector.matchedResult().matchedProperties.size() - 1;
     collectMatchingAuthorRules(collector, includeEmptyRules, applyAuthorStyles, ignoreCascadeScope);
     collector.sortAndTransferMatchedRules();
 }
 
+bool ScopedStyleResolver::matchesAnyAuthorRules(ElementRuleCollector& collector, bool includeEmptyRules, bool applyAuthorStyles)
+{
+    collector.clearMatchedRules();
+    collector.matchedResult().ranges.lastAuthorRule = collector.matchedResult().matchedProperties.size() - 1;
+    collectMatchingAuthorRules(collector, includeEmptyRules, applyAuthorStyles, ignoreCascadeScope);
+    return collector.matchedResult().matchedRules.size();
+}
+
 void ScopedStyleResolver::collectMatchingAuthorRules(ElementRuleCollector& collector, bool includeEmptyRules, bool applyAuthorStyles, CascadeScope cascadeScope, CascadeOrder cascadeOrder)
 {
     if (!m_authorStyle)
         return;
 
     const ContainerNode* scopingNode = &m_scopingNode;
     unsigned behaviorAtBoundary = SelectorChecker::DoesNotCrossBoundary;
 
     if (!applyAuthorStyles)
         behaviorAtBoundary |= SelectorChecker::ScopeContainsLastMatchedElement;
@@ skipping 18 matching lines @@
 
 void ScopedStyleResolver::collectViewportRulesTo(StyleResolver* resolver) const
 {
     // Only consider the global author RuleSet for @viewport rules.
     ASSERT(m_scopingNode.isDocumentNode());
     if (m_authorStyle)
         resolver->viewportStyleResolver()->collectViewportRules(m_authorStyle.get(), ViewportStyleResolver::AuthorOrigin);
 }
 
 } // namespace WebCore