Avoid using transparency layer for fancy borders.

Source/core/rendering/RenderBoxModelObject.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 20 matching lines @@
 namespace WebCore {
 
 // Modes for some of the line-related functions.
 enum LinePositionMode { PositionOnContainingLine, PositionOfInteriorLineBoxes };
 enum LineDirectionMode { HorizontalLine, VerticalLine };
 typedef unsigned BorderEdgeFlags;
 
 enum BackgroundBleedAvoidance {
     BackgroundBleedNone,
     BackgroundBleedShrinkBackground,
-    BackgroundBleedUseTransparencyLayer,
+    BackgroundBleedClipBackground,
     BackgroundBleedBackgroundOverBorder
 };
 
 enum ContentChangeType {
     ImageChanged,
     MaskImageChanged,
     CanvasChanged,
     CanvasPixelsChanged,
     VideoChanged,
     FullScreenChanged
@@ skipping 277 matching lines @@
     void drawBoxSideFromPath(GraphicsContext*, const LayoutRect&, const Path&, const class BorderEdge[],
                             float thickness, float drawThickness, BoxSide, const RenderStyle*,
                             Color, EBorderStyle, BackgroundBleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge);
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderBoxModelObject, isBoxModelObject());
 
 } // namespace WebCore
 
 #endif // RenderBoxModelObject_h