Store [-webkit-]perspective-origin as a LengthPoint.

Source/core/rendering/style/StyleRareNonInheritedData.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
@@ skipping 78 matching lines @@
     bool transitionDataEquivalent(const StyleRareNonInheritedData&) const;
     bool hasFilters() const;
     bool hasOpacity() const { return opacity < 1; }
 
     float opacity; // Whether or not we're transparent.
 
     float m_aspectRatioDenominator;
     float m_aspectRatioNumerator;
 
     float m_perspective;
-    Length m_perspectiveOriginX;
-    Length m_perspectiveOriginY;
+    LengthPoint m_perspectiveOrigin;
 
     LineClampValue lineClamp; // An Apple extension.
     DraggableRegionMode m_draggableRegionMode;
 
     DataRef<StyleDeprecatedFlexibleBoxData> m_deprecatedFlexibleBox; // Flexible box properties
     DataRef<StyleFlexibleBoxData> m_flexibleBox;
     DataRef<StyleMarqueeData> m_marquee; // Marquee properties
     DataRef<StyleMultiColData> m_multiCol; //  CSS3 multicol properties
     DataRef<StyleTransformData> m_transform; // Transform properties (rotate, scale, skew, etc.)
     DataRef<StyleWillChangeData> m_willChange; // CSS Will Change
@@ skipping 99 matching lines @@
     unsigned m_hasInlineTransform : 1;
 
 private:
     StyleRareNonInheritedData();
     StyleRareNonInheritedData(const StyleRareNonInheritedData&);
 };
 
 } // namespace blink
 
 #endif // StyleRareNonInheritedData_h