[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 5a20ac5f6bc59b6d99bac0a26db3c912f0e43255..231cee8e96a8a52440d35c3e5615b0c02eb88b17 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:
     ~AnimatableClipPathOperation() override { }
-    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:
-    PassRefPtrWillBeRawPtr<AnimatableValue> interpolateTo(const AnimatableValue*, double fraction) const override;
+    AnimatableValue* interpolateTo(const AnimatableValue*, double fraction) const override;
     bool usesDefaultInterpolationWith(const AnimatableValue*) const override;
 
 private: