Make classes and structures in Source/core/animation fast-allocated.

Source/core/animation/AnimationTimeline.h

Index: Source/core/animation/AnimationTimeline.h
diff --git a/Source/core/animation/AnimationTimeline.h b/Source/core/animation/AnimationTimeline.h
index 1277d4debf4e9ab6ba8f8de60b6ff785a52f007b..6201935b13170da587597f830b077ca14594a311 100644
--- a/Source/core/animation/AnimationTimeline.h
+++ b/Source/core/animation/AnimationTimeline.h
@@ -53,7 +53,7 @@ class CORE_EXPORT AnimationTimeline : public RefCountedWillBeGarbageCollectedFin
     DEFINE_WRAPPERTYPEINFO();
 public:
     class PlatformTiming : public NoBaseWillBeGarbageCollectedFinalized<PlatformTiming> {
-
+        WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(PlatformTiming);
     public:
         // Calls AnimationTimeline's wake() method after duration seconds.
         virtual void wakeAfter(double duration) = 0;