Use alias_for with trivial property aliases

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 339 matching lines @@
         return createFromColor(property, style);
     case CSSPropertyBorderTopLeftRadius:
         return createFromLengthSize(style.borderTopLeftRadius(), style);
     case CSSPropertyBorderTopRightRadius:
         return createFromLengthSize(style.borderTopRightRadius(), style);
     case CSSPropertyBorderTopWidth:
         return createFromDouble(style.borderTopWidth());
     case CSSPropertyBottom:
         return createFromLength(style.bottom(), style);
     case CSSPropertyBoxShadow:
-    case CSSPropertyWebkitBoxShadow:
         return AnimatableShadow::create(style.boxShadow());
     case CSSPropertyClip:
         if (style.hasAutoClip())
             return AnimatableUnknown::create(CSSPrimitiveValue::create(CSSValueAuto));
         return createFromLengthBox(style.clip(), style);
     case CSSPropertyColor:
         return createFromColor(property, style);
     case CSSPropertyFillOpacity:
         return createFromDouble(style.fillOpacity());
     case CSSPropertyFill:
@@ skipping 194 matching lines @@
         return createFromLength(style.svgStyle().ry(), style);
     case CSSPropertyZIndex:
         return createFromDouble(style.zIndex());
     default:
         ASSERT_NOT_REACHED();
         return nullptr;
     }
 }
 
 } // namespace blink