DevTools: defer styles delta calculation to until the end of the task.

Source/core/inspector/InspectorCSSAgent.h

 /*
  * Copyright (C) 2010, 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.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 90 matching lines @@
     {
         return adoptPtr(new InspectorCSSAgent(domAgent, pageAgent, resourceAgent));
     }
     virtual ~InspectorCSSAgent();
 
     bool forcePseudoState(Element*, CSSSelector::PseudoType);
     virtual void setFrontend(InspectorFrontend*) OVERRIDE;
     virtual void clearFrontend() OVERRIDE;
     virtual void discardAgent() OVERRIDE;
     virtual void restore() OVERRIDE;
+    virtual void flushPendingFrontendMessages() OVERRIDE;
     virtual void enable(ErrorString*, PassRefPtr<EnableCallback>) OVERRIDE;
     virtual void disable(ErrorString*) OVERRIDE;
     void reset();
     void didCommitLoad(LocalFrame*, DocumentLoader*);
     void mediaQueryResultChanged();
     void willMutateRules();
     void didMutateRules(CSSStyleSheet*);
     void willMutateStyle();
     void didMutateStyle(CSSStyleDeclaration*, bool);
 
@@ skipping 68 matching lines @@
 
     InspectorFrontend::CSS* m_frontend;
     InspectorDOMAgent* m_domAgent;
     InspectorPageAgent* m_pageAgent;
     InspectorResourceAgent* m_resourceAgent;
 
     IdToInspectorStyleSheet m_idToInspectorStyleSheet;
     HashMap<CSSStyleSheet*, RefPtr<InspectorStyleSheet> > m_cssStyleSheetToInspectorStyleSheet;
     typedef HashMap<Document*, OwnPtr<HashSet<CSSStyleSheet*> > > DocumentStyleSheets;
     DocumentStyleSheets m_documentToCSSStyleSheets;
+    HashSet<Document*> m_invalidatedDocuments;
 
     NodeToInspectorStyleSheet m_nodeToInspectorStyleSheet;
     HashMap<RefPtr<Document>, RefPtr<InspectorStyleSheet> > m_documentToViaInspectorStyleSheet; // "via inspector" stylesheets
     NodeIdToForcedPseudoState m_nodeIdToForcedPseudoState;
 
     RefPtr<CSSStyleSheet> m_inspectorUserAgentStyleSheet;
 
     int m_lastStyleSheetId;
     int m_styleSheetsPendingMutation;
     bool m_styleDeclarationPendingMutation;
     bool m_creatingViaInspectorStyleSheet;
     bool m_isSettingStyleSheetText;
 
     friend class EnableResourceClient;
     friend class StyleSheetBinder;
 };
 
 
 } // namespace WebCore
 
 #endif // !defined(InspectorCSSAgent_h)