Store [-webkit-]transform-origin as a TransformOrigin.

Source/core/rendering/style/StyleTransformData.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 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef StyleTransformData_h
 #define StyleTransformData_h
 
-#include "platform/Length.h"
+#include "core/rendering/style/TransformOrigin.h"
 #include "platform/transforms/TransformOperations.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 
 namespace blink {
 
 class StyleTransformData : public RefCounted<StyleTransformData> {
 public:
     static PassRefPtr<StyleTransformData> create() { return adoptRef(new StyleTransformData); }
     PassRefPtr<StyleTransformData> copy() const { return adoptRef(new StyleTransformData(*this)); }
 
     bool operator==(const StyleTransformData& o) const;
     bool operator!=(const StyleTransformData& o) const
     {
         return !(*this == o);
     }
 
     TransformOperations m_operations;
-    Length m_x;
-    Length m_y;
-    float m_z;
+    TransformOrigin m_origin;
 
 private:
     StyleTransformData();
     StyleTransformData(const StyleTransformData&);
 };
 
 } // namespace blink
 
 #endif // StyleTransformData_h