Clear active tree scopes on StyleEngine::didDetach().

third_party/WebKit/Source/core/dom/StyleEngine.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 169 matching lines @@
   void setRuleUsageTracker(StyleRuleUsageTracker*);
 
   StyleResolver& ensureResolver() {
     updateActiveStyle();
     if (!m_resolver)
       createResolver();
     return *m_resolver;
   }
 
   bool hasResolver() const { return m_resolver; }
-  void clearResolver();
 
   StyleInvalidator& styleInvalidator() { return m_styleInvalidator; }
   bool mediaQueryAffectedByViewportChange();
   bool mediaQueryAffectedByDeviceChange();
   bool hasViewportDependentMediaQueries() const {
     return !m_globalRuleSet.ruleFeatureSet()
                 .viewportDependentMediaQueryResults()
                 .isEmpty();
   }
 
@@ skipping 79 matching lines @@
   Document& document() const { return *m_document; }
 
   typedef HeapHashSet<Member<TreeScope>> UnorderedTreeScopeSet;
 
   void mediaQueryAffectingValueChanged(UnorderedTreeScopeSet&);
   const RuleFeatureSet& ruleFeatureSet() const {
     return m_globalRuleSet.ruleFeatureSet();
   }
 
   void createResolver();
+  void clearResolvers();
 
   CSSStyleSheet* parseSheet(Element&,
                             const String& text,
                             TextPosition startPosition);
 
   const DocumentStyleSheetCollection& documentStyleSheetCollection() const {
     DCHECK(m_documentStyleSheetCollection);
     return *m_documentStyleSheetCollection;
   }
 
@@ skipping 65 matching lines @@
 
   std::unique_ptr<StyleResolverStats> m_styleResolverStats;
   unsigned m_styleForElementCount = 0;
 
   friend class StyleEngineTest;
 };
 
 }  // namespace blink
 
 #endif