Reland "Avoid layout/full-repaint on view height change if possible"

Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 243 matching lines @@
     void flushAnyPendingPostLayoutTasks();
 
     virtual bool shouldSuspendScrollAnimations() const OVERRIDE;
     virtual void scrollbarStyleChanged(int newStyle, bool forceUpdate) OVERRIDE;
 
     RenderBox* embeddedContentBox() const;
 
     void setTracksRepaints(bool);
     bool isTrackingRepaints() const { return m_isTrackingRepaints; }
     void resetTrackedRepaints();
+    const Vector<IntRect>& trackedRepaintRects() const { return m_trackedRepaintRects; }
     String trackedRepaintRectsAsText() const;
 
     typedef HashSet<ScrollableArea*> ScrollableAreaSet;
     // Returns whether the scrollable area has just been newly added.
     bool addScrollableArea(ScrollableArea*);
     // Returns whether the scrollable area has just been removed.
     bool removeScrollableArea(ScrollableArea*);
     bool containsScrollableArea(const ScrollableArea*) const;
     const ScrollableAreaSet* scrollableAreas() const { return m_scrollableAreas.get(); }
 
@@ skipping 273 matching lines @@
         m_view->setCanRepaintDuringPerformLayout(m_originalValue);
     }
 private:
     FrameView* m_view;
     bool m_originalValue;
 };
 
 } // namespace WebCore
 
 #endif // FrameView_h