Reland "Recompute overflow after transform changes"

Source/core/rendering/RenderLayerScrollableArea.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 107 matching lines @@
 
     // FIXME: We shouldn't allow access to m_overflowRect outside this class.
     LayoutRect overflowRect() const { return m_overflowRect; }
 
     void scrollToOffset(const IntSize& scrollOffset, ScrollOffsetClamping = ScrollOffsetUnclamped);
     void scrollToXOffset(int x, ScrollOffsetClamping clamp = ScrollOffsetUnclamped) { scrollToOffset(IntSize(x, scrollYOffset()), clamp); }
     void scrollToYOffset(int y, ScrollOffsetClamping clamp = ScrollOffsetUnclamped) { scrollToOffset(IntSize(scrollXOffset(), y), clamp); }
 
     void updateAfterLayout();
     void updateAfterStyleChange(const RenderStyle*);
+    void updateAfterOverflowRecalc();
 
     virtual void updateAfterCompositingChange() OVERRIDE;
 
     bool hasScrollbar() const { return m_hBar || m_vBar; }
 
     // FIXME: This should be removed.
     bool hasScrollCorner() const { return m_scrollCorner; }
 
     void resize(const PlatformEvent&, const LayoutSize&);
     IntSize offsetFromResizeCorner(const IntPoint& absolutePoint) const;
@@ skipping 117 matching lines @@
     // Renderers to hold our custom scroll corner.
     RenderScrollbarPart* m_scrollCorner;
 
     // Renderers to hold our custom resizer.
     RenderScrollbarPart* m_resizer;
 };
 
 } // Namespace WebCore
 
 #endif // RenderLayerScrollableArea_h