Add infrastructure for partial layouts

Source/core/page/FrameView.h

Index: Source/core/page/FrameView.h
diff --git a/Source/core/page/FrameView.h b/Source/core/page/FrameView.h
index 6440cc93f247bbfd3e61c887f6c4bccb6ebf5e28..b398c46b5b67aafb555170e5561e1ba077ba0e1d 100644
--- a/Source/core/page/FrameView.h
+++ b/Source/core/page/FrameView.h
@@ -337,6 +337,11 @@ public:
     // DEPRECATED: Use viewportConstrainedVisibleContentRect() instead.
     IntSize scrollOffsetForFixedPosition() const;
 
+    bool canStopPartialLayout() const { return m_canStopPartialLayout; }
+    void checkPartialLayoutComplete(RenderObject*);
+    void setStopLayoutAtRenderer(RenderObject* renderer) { m_stopLayoutAtRenderer = renderer; }
+    void resetPartialLayoutState() { m_stopLayoutAtRenderer = 0; m_canStopPartialLayout = false; }
+
 protected:
     virtual bool scrollContentsFastPath(const IntSize& scrollDelta, const IntRect& rectToScroll, const IntRect& clipRect);
     virtual void scrollContentsSlowPath(const IntRect& updateRect);
@@ -527,6 +532,9 @@ private:
     bool m_hasSoftwareFilters;
 
     float m_visibleContentScaleFactor;
+
+    bool m_canStopPartialLayout;
+    RenderObject* m_stopLayoutAtRenderer;
 };
 
 inline void FrameView::incrementVisuallyNonEmptyCharacterCount(unsigned count)