Add infrastructure for partial layouts

Source/core/dom/Document.h

Index: Source/core/dom/Document.h
diff --git a/Source/core/dom/Document.h b/Source/core/dom/Document.h
index b5fc9e6759344aaab4c94996e5abf9f17d07b9cc..4f54496b2f1fa5aad33061107c8d049426b94fe5 100644
--- a/Source/core/dom/Document.h
+++ b/Source/core/dom/Document.h
@@ -489,6 +489,7 @@ public:
     void updateStyleForNodeIfNeeded(Node*);
     void updateLayout();
     void updateLayoutIgnorePendingStylesheets();
+    void partialUpdateLayoutIgnorePendingStylesheets(Node*);
     PassRefPtr<RenderStyle> styleForElementIgnoringPendingStylesheets(Element*);
     PassRefPtr<RenderStyle> styleForPage(int pageIndex);
 
@@ -1119,6 +1120,8 @@ private:
 
     void seamlessParentUpdatedStylesheets();
 
+    void recalcStyleForLayoutIgnoringPendingStylesheets();
+
     PassRefPtr<NodeList> handleZeroPadding(const HitTestRequest&, HitTestResult&) const;
 
     void loadEventDelayTimerFired(Timer<Document>*);