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 aac8c9f185a3d2b403500523bcbcff92372eac6d..c3b8692b456ea354e9a52341cfe0c4338367434f 100644
--- a/Source/core/dom/Document.h
+++ b/Source/core/dom/Document.h
@@ -488,6 +488,7 @@ public:
     void updateStyleForNodeIfNeeded(Node*);
     void updateLayout();
     void updateLayoutIgnorePendingStylesheets();
+    void partialUpdateLayoutIgnorePendingStylesheets(Node*);
     PassRefPtr<RenderStyle> styleForElementIgnoringPendingStylesheets(Element*);
     PassRefPtr<RenderStyle> styleForPage(int pageIndex);
 
@@ -1117,6 +1118,8 @@ private:
 
     void seamlessParentUpdatedStylesheets();
 
+    void recalcStyleForLayoutIgnoringPendingStylesheets();
+
     PassRefPtr<NodeList> handleZeroPadding(const HitTestRequest&, HitTestResult&) const;
 
     void loadEventDelayTimerFired(Timer<Document>*);