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

Source/core/animation/animatable/AnimatableClipPathOperation.h

Index: Source/core/animation/animatable/AnimatableClipPathOperation.h
diff --git a/Source/core/animation/animatable/AnimatableClipPathOperation.h b/Source/core/animation/animatable/AnimatableClipPathOperation.h
index b0e169a982b0047f02adadcbb64f53e4058b56b4..78de04b76d763aa6e0883405d3db8189c4d7e838 100644
--- a/Source/core/animation/animatable/AnimatableClipPathOperation.h
+++ b/Source/core/animation/animatable/AnimatableClipPathOperation.h
@@ -40,16 +40,16 @@ namespace blink {
 class CORE_EXPORT AnimatableClipPathOperation final : public AnimatableValue {
 public:
     virtual ~AnimatableClipPathOperation() { }
-    static PassRefPtrWillBeRawPtr<AnimatableClipPathOperation> create(ClipPathOperation* operation)
+    static AnimatableClipPathOperation* create(ClipPathOperation* operation)
     {
-        return adoptRefWillBeNoop(new AnimatableClipPathOperation(operation));
+        return new AnimatableClipPathOperation(operation);
     }
     ClipPathOperation* clipPathOperation() const { return m_operation.get(); }
 
     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: