Allow proper highlighting on universal overflow scroll.

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 159 matching lines @@
     void updateLayerPositions(RenderGeometryMap*, const RenderLayerModelObject* paintInvalidationContainer, UpdateLayerPositionsFlags = CheckForRepaint);
 
     bool isPaginated() const { return m_isPaginated; }
     RenderLayer* enclosingPaginationLayer() const { return m_enclosingPaginationLayer; }
 
     void updateTransform();
     RenderLayer* renderingContextRoot();
 
     const LayoutSize& offsetForInFlowPosition() const { return m_offsetForInFlowPosition; }
 
+    enum PresenceOfBlockSelectionGaps {
+        LayerHasBlockSelectionGaps,
+        LayerDoesNotHaveBlockSelectionGaps
+    };
+
+    PresenceOfBlockSelectionGaps rendererHasBlockSelectionGaps();

[Ian Vollick, 2014/06/05 18:28:41]

Can you replace the implementation of hasBlockSelectionGapBounds instead of
creating a very similar function here?

[hartmanng, 2014/06/05 20:28:03]

Done.

+    void blockSelectionGapsBoundsChanged();
     void addBlockSelectionGapsBounds(const LayoutRect&);
     void clearBlockSelectionGapsBounds();
     void repaintBlockSelectionGaps();
     bool hasBlockSelectionGapBounds() const;
 
     RenderLayerStackingNode* stackingNode() { return m_stackingNode.get(); }
     const RenderLayerStackingNode* stackingNode() const { return m_stackingNode.get(); }
 
     bool subtreeIsInvisible() const { return !hasVisibleContent() && !hasVisibleDescendant(); }
 
@@ skipping 540 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