Don't rely on values computed as a side effect of paint.

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 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 3295 matching lines @@
         rect.move(-box->scrolledContentOffset());
         if (!scrollableArea()->usesCompositedScrolling())
             rect.intersect(box->overflowClipRect(LayoutPoint()));
     }
     if (renderer()->hasClip())
         rect.intersect(toRenderBox(renderer())->clipRect(LayoutPoint()));
     if (!rect.isEmpty())
         renderer()->repaintRectangle(rect);
 }
 
-bool RenderLayer::hasBlockSelectionGapBounds() const
-{
-    return !m_blockSelectionGapsBounds.isEmpty();
-}
-
 bool RenderLayer::intersectsDamageRect(const LayoutRect& layerBounds, const LayoutRect& damageRect, const RenderLayer* rootLayer, const LayoutPoint* offsetFromRoot) const
 {
     // Always examine the canvas and the root.
     // FIXME: Could eliminate the isRoot() check if we fix background painting so that the RenderView
     // paints the root's background.
     if (isRootLayer() || renderer()->isRoot())
         return true;
 
     // If we aren't an inline flow, and our layer bounds do intersect the damage rect, then we
     // can go ahead and return true.
@@ skipping 825 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif