Properly repaint RenderLayer's descendants when it moves

Source/core/rendering/RenderLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. 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>
@@ skipping 139 matching lines @@
     RenderLayerCompositor* compositor() const;
 
     // Notification from the renderer that its content changed (e.g. current frame of image changed).
     // Allows updates of layer content without invalidating paint.
     void contentChanged(ContentChangeType);
 
     enum UpdateLayerPositionsFlag {
         CheckForPaintInvalidation = 1 << 0,
         NeedsFullPaintInvalidationInBacking = 1 << 1,
         UpdatePagination = 1 << 2,
+        ForceMayNeedPaintInvalidation = 1 << 3,
     };
     typedef unsigned UpdateLayerPositionsFlags;
 
     void updateLayerPositionsAfterLayout(const RenderLayer* rootLayer, UpdateLayerPositionsFlags);
     void updateLayerPositionsAfterOverflowScroll();
     void updateLayerPositionsAfterDocumentScroll();
 
     // FIXME: Should updateLayerPositions be private?
     void updateLayerPositionRecursive(UpdateLayerPositionsFlags = CheckForPaintInvalidation);
 
@@ skipping 560 matching lines @@
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const WebCore::RenderLayer*);
 void showLayerTree(const WebCore::RenderObject*);
 #endif
 
 #endif // RenderLayer_h