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

Source/core/animation/css/CSSAnimatableValueFactory.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 453 matching lines @@
         return createFromFillLayers<CSSPropertyWebkitMaskImage>(style.maskLayers(), style);
     case CSSPropertyWebkitMaskPositionX:
         return createFromFillLayers<CSSPropertyWebkitMaskPositionX>(style.maskLayers(), style);
     case CSSPropertyWebkitMaskPositionY:
         return createFromFillLayers<CSSPropertyWebkitMaskPositionY>(style.maskLayers(), style);
     case CSSPropertyWebkitMaskSize:
         return createFromFillLayers<CSSPropertyWebkitMaskSize>(style.maskLayers(), style);
     case CSSPropertyPerspective:
         return createFromDouble(style.perspective());
     case CSSPropertyPerspectiveOrigin:
-        return AnimatableLengthPoint::create(
-            createFromLength(style.perspectiveOriginX(), style),
-            createFromLength(style.perspectiveOriginY(), style));
+        return createFromLengthPoint(style.perspectiveOrigin(), style);
     case CSSPropertyShapeOutside:
         return createFromShapeValue(style.shapeOutside());
     case CSSPropertyShapeMargin:
         return createFromLength(style.shapeMargin(), style);
     case CSSPropertyShapeImageThreshold:
         return createFromDouble(style.shapeImageThreshold());
     case CSSPropertyWebkitTextStrokeColor:
         return createFromColor(property, style);
     case CSSPropertyTransform:
         return AnimatableTransform::create(style.transform());
@@ skipping 19 matching lines @@
     case CSSPropertyZoom:
         return createFromDouble(style.zoom());
     default:
         ASSERT_NOT_REACHED();
         // This return value is to avoid a release crash if possible.
         return AnimatableUnknown::create(nullptr);
     }
 }
 
 } // namespace blink