[Oilpan] Migrate most classes under core/animations to Oilpan heap.

Source/core/animation/animatable/AnimatableVisibility.h

Index: Source/core/animation/animatable/AnimatableVisibility.h
diff --git a/Source/core/animation/animatable/AnimatableVisibility.h b/Source/core/animation/animatable/AnimatableVisibility.h
index a70c84e99f02ad6bd7576f19879f00368a3ef0f6..9f693ab6206d545710902b7b1f418927fb66f91e 100644
--- a/Source/core/animation/animatable/AnimatableVisibility.h
+++ b/Source/core/animation/animatable/AnimatableVisibility.h
@@ -40,9 +40,9 @@ namespace blink {
 class CORE_EXPORT AnimatableVisibility final : public AnimatableValue {
 public:
     virtual ~AnimatableVisibility() { }
-    static PassRefPtrWillBeRawPtr<AnimatableVisibility> create(EVisibility visibility)
+    static AnimatableVisibility* create(EVisibility visibility)
     {
-        return adoptRefWillBeNoop(new AnimatableVisibility(visibility));
+        return new AnimatableVisibility(visibility);
     }
 
     EVisibility visibility() const { return m_visibility; }
@@ -50,7 +50,7 @@ public:
     DEFINE_INLINE_VIRTUAL_TRACE() { AnimatableValue::trace(visitor); }
 
 protected:
-    virtual PassRefPtrWillBeRawPtr<AnimatableValue> interpolateTo(const AnimatableValue*, double fraction) const override;
+    virtual AnimatableValue* interpolateTo(const AnimatableValue*, double fraction) const override;
     virtual bool usesDefaultInterpolationWith(const AnimatableValue*) const override;
 
 private: