Remove backface visibility

sky/engine/core/rendering/style/RenderStyleConstants.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 186 matching lines @@
 enum EPointerEvents {
     PE_NONE, PE_AUTO, PE_STROKE, PE_FILL, PE_PAINTED, PE_VISIBLE,
     PE_VISIBLE_STROKE, PE_VISIBLE_FILL, PE_VISIBLE_PAINTED, PE_BOUNDINGBOX,
     PE_ALL
 };
 
 enum ETransformStyle3D {
     TransformStyle3DFlat, TransformStyle3DPreserve3D
 };
 
-enum EBackfaceVisibility {
-    BackfaceVisibilityVisible, BackfaceVisibilityHidden
-};
-
 enum Hyphens { HyphensNone, HyphensManual, HyphensAuto };
 
 enum TextEmphasisFill { TextEmphasisFillFilled, TextEmphasisFillOpen };
 
 enum TextEmphasisMark { TextEmphasisMarkNone, TextEmphasisMarkAuto, TextEmphasisMarkDot, TextEmphasisMarkCircle, TextEmphasisMarkDoubleCircle, TextEmphasisMarkTriangle, TextEmphasisMarkSesame, TextEmphasisMarkCustom };
 
 enum TextEmphasisPosition { TextEmphasisPositionOver, TextEmphasisPositionUnder };
 
 enum TextOrientation { TextOrientationVerticalRight, TextOrientationUpright, TextOrientationSideways, TextOrientationSidewaysRight };
 
@@ skipping 57 matching lines @@
 static const float maximumAllowedFontSize = 1000000.0f;
 
 enum TextIndentLine { TextIndentFirstLine, TextIndentEachLine };
 enum TextIndentType { TextIndentNormal, TextIndentHanging };
 
 enum CSSBoxType { BoxMissing = 0, MarginBox, BorderBox, PaddingBox, ContentBox };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_RENDERING_STYLE_RENDERSTYLECONSTANTS_H_