Make setNeedsActiveStyleUpdate mark treescope dirty only.

third_party/WebKit/Source/core/css/CSSStyleSheet.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2012 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 148 matching lines @@
   DCHECK(m_contents->isMutable());
   DCHECK_LE(m_contents->clientSize(), 1u);
 
   didMutate(PartialRuleUpdate);
 }
 
 void CSSStyleSheet::didMutate(StyleSheetUpdateType updateType) {
   Document* owner = ownerDocument();
   if (!owner)
     return;
+  if (ownerNode() && ownerNode()->isConnected())
+    owner->styleEngine().setNeedsActiveStyleUpdate(ownerNode()->treeScope());
+
+  // TODO(rune@opera.com): resolverChanged() can be removed once stylesheet
+  // updates are async. https://crbug.com/567021
 
   // Need FullStyleUpdate when insertRule or deleteRule,
   // because StyleSheetCollection::analyzeStyleSheetChange cannot detect partial
   // rule update.
   StyleResolverUpdateMode updateMode =
       updateType != PartialRuleUpdate ? AnalyzedStyleUpdate : FullStyleUpdate;
-  owner->styleEngine().setNeedsActiveStyleUpdate(this, updateMode);
+  owner->styleEngine().resolverChanged(updateMode);
 }
 
 void CSSStyleSheet::reattachChildRuleCSSOMWrappers() {
   for (unsigned i = 0; i < m_childRuleCSSOMWrappers.size(); ++i) {
     if (!m_childRuleCSSOMWrappers[i])
       continue;
     m_childRuleCSSOMWrappers[i]->reattach(m_contents->ruleAt(i));
   }
 }
 
@@ skipping 252 matching lines @@
   visitor->trace(m_deviceDependentMediaQueryResults);
   visitor->trace(m_ownerNode);
   visitor->trace(m_ownerRule);
   visitor->trace(m_mediaCSSOMWrapper);
   visitor->trace(m_childRuleCSSOMWrappers);
   visitor->trace(m_ruleListCSSOMWrapper);
   StyleSheet::trace(visitor);
 }
 
 }  // namespace blink