Allow proper highlighting on universal overflow scroll.

Source/core/rendering/compositing/GraphicsLayerUpdater.cpp

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 76 matching lines @@
         mapping->updateGraphicsLayerGeometry(updateType, compositingContainer);
 
         updateType = mapping->updateTypeForChildren(updateType);
         mapping->clearNeedsGraphicsLayerUpdate();
 
         if (!layer.parent())
             layer.compositor()->updateRootLayerPosition();
 
         if (mapping->hasUnpositionedOverflowControlsLayers())
             layer.scrollableArea()->positionOverflowControls(IntSize());
+
+        mapping->updateScrollingBlockSelection();
     }
 
     UpdateContext childContext(context, layer);
     for (RenderLayer* child = layer.firstChild(); child; child = child->nextSibling())
         update(*child, updateType, childContext);
 }
 
 #if ASSERT_ENABLED
 
 void GraphicsLayerUpdater::assertNeedsToUpdateGraphicsLayerBitsCleared(RenderLayer& layer)
 {
     if (layer.hasCompositedLayerMapping())
         layer.compositedLayerMapping()->assertNeedsToUpdateGraphicsLayerBitsCleared();
 
     for (RenderLayer* child = layer.firstChild(); child; child = child->nextSibling())
         assertNeedsToUpdateGraphicsLayerBitsCleared(*child);
 }
 
 #endif
 
 } // namespace WebCore