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

Source/core/inspector/InspectorCSSAgent.h

Index: Source/core/inspector/InspectorCSSAgent.h
diff --git a/Source/core/inspector/InspectorCSSAgent.h b/Source/core/inspector/InspectorCSSAgent.h
index d10435884235da226803b8fc0c132d3f79c636e4..dabeb330ef53377cfe1b3424228950e918f2d57e 100644
--- a/Source/core/inspector/InspectorCSSAgent.h
+++ b/Source/core/inspector/InspectorCSSAgent.h
@@ -117,9 +117,10 @@ public:
     void didMutateRules(CSSStyleSheet*);
     void willMutateStyle();
     void didMutateStyle(CSSStyleDeclaration*, bool);
+    void didProcessTask();
 
-public:
     void activeStyleSheetsUpdated(Document*);
+    void documentDisposed(Document*);
     void frameDetachedFromParent(LocalFrame*);
 
     virtual void getComputedStyleForNode(ErrorString*, int nodeId, RefPtr<TypeBuilder::Array<TypeBuilder::CSS::CSSComputedStyleProperty> >&) OVERRIDE;
@@ -159,8 +160,9 @@ private:
     void collectAllDocumentStyleSheets(Document*, Vector<CSSStyleSheet*>&);
     void collectStyleSheets(CSSStyleSheet*, Vector<CSSStyleSheet*>&);
 
-    void updateActiveStyleSheetsForDocument(Document*, StyleSheetsUpdateType);
-    void updateActiveStyleSheets(LocalFrame*, const Vector<CSSStyleSheet*>&, StyleSheetsUpdateType);
+    void updateActiveStyleSheets(Document*, StyleSheetsUpdateType);
+    void setActiveStyleSheets(Document*, const Vector<CSSStyleSheet*>&, StyleSheetsUpdateType);
+    void validateFrontendStylesheets();
 
     void collectPlatformFontsForRenderer(RenderText*, HashCountedSet<String>*);
 
@@ -194,7 +196,9 @@ private:
 
     IdToInspectorStyleSheet m_idToInspectorStyleSheet;
     HashMap<CSSStyleSheet*, RefPtr<InspectorStyleSheet> > m_cssStyleSheetToInspectorStyleSheet;
-    HashMap<LocalFrame*, OwnPtr<HashSet<CSSStyleSheet*> > > m_frameToCSSStyleSheets;
+    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