CC Animation: Expose TargetProperty enum to be aliased in Blink Platform.

cc/animation/element_animations.h

Index: cc/animation/element_animations.h
diff --git a/cc/animation/element_animations.h b/cc/animation/element_animations.h
index 90090cfebfdb36f7acfe80e790436248e6b7e3d3..7258683d4d214f3fe97faa6a2fe300ccc0d31813 100644
--- a/cc/animation/element_animations.h
+++ b/cc/animation/element_animations.h
@@ -95,13 +95,13 @@ class CC_EXPORT ElementAnimations : public AnimationDelegate,
 
   // AnimationDelegate implementation
   void NotifyAnimationStarted(base::TimeTicks monotonic_time,
-                              Animation::TargetProperty target_property,
+                              AnimationTargetProperty target_property,
                               int group) override;
   void NotifyAnimationFinished(base::TimeTicks monotonic_time,
-                               Animation::TargetProperty target_property,
+                               AnimationTargetProperty target_property,
                                int group) override;
   void NotifyAnimationAborted(base::TimeTicks monotonic_time,
-                              Animation::TargetProperty target_property,
+                              AnimationTargetProperty target_property,
                               int group) override;
 
   // LayerAnimationValueProvider implementation.