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

Source/core/animation/css/CSSAnimatableValueFactory.cpp

Index: Source/core/animation/css/CSSAnimatableValueFactory.cpp
diff --git a/Source/core/animation/css/CSSAnimatableValueFactory.cpp b/Source/core/animation/css/CSSAnimatableValueFactory.cpp
index dc68f5d3e9e3bbd671024e25fd95179577ae7c0b..988c46d761cc408445b2947007632fc058dea08a 100644
--- a/Source/core/animation/css/CSSAnimatableValueFactory.cpp
+++ b/Source/core/animation/css/CSSAnimatableValueFactory.cpp
@@ -471,9 +471,7 @@ PassRefPtrWillBeRawPtr<AnimatableValue> CSSAnimatableValueFactory::create(CSSPro
     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: