Remove backface visibility

sky/engine/core/rendering/RenderBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 Apple 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 56 matching lines @@
 };
 
 class RenderBox : public RenderBoxModelObject {
 public:
     explicit RenderBox(ContainerNode*);
 
     // hasAutoZIndex only returns true if the element is positioned or a flex-item since
     // position:static elements that are not flex-items get their z-index coerced to auto.
     virtual LayerType layerTypeRequired() const
     {
-        if (isPositioned() || createsGroup() || hasClipPath() || hasTransform() || hasHiddenBackface() || !style()->hasAutoZIndex())
+        if (isPositioned() || createsGroup() || hasClipPath() || hasTransform() || !style()->hasAutoZIndex())
             return NormalLayer;
         if (hasOverflowClip())
             return OverflowClipLayer;
         return NoLayer;
     }
 
     void destroyLayer();
     void createLayer(LayerType);
     bool hasSelfPaintingLayer() const;
     RenderLayer* layer() const { return m_layer.get(); }
@@ skipping 528 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != 0))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_RENDERING_RENDERBOX_H_