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

Source/core/animation/animatable/AnimatableShadow.h

Index: Source/core/animation/animatable/AnimatableShadow.h
diff --git a/Source/core/animation/animatable/AnimatableShadow.h b/Source/core/animation/animatable/AnimatableShadow.h
index ba93fd1f7ef9563cbe6155db46b0365f37084ee9..a69f470ff3c0f0247a8bb85dfab937ac1322ffb4 100644
--- a/Source/core/animation/animatable/AnimatableShadow.h
+++ b/Source/core/animation/animatable/AnimatableShadow.h
@@ -39,16 +39,16 @@ namespace blink {
 class AnimatableShadow final : public AnimatableValue {
 public:
     ~AnimatableShadow() override { }
-    static PassRefPtrWillBeRawPtr<AnimatableShadow> create(PassRefPtr<ShadowList> shadowList, const Color& currentColor)
+    static AnimatableShadow* create(PassRefPtr<ShadowList> shadowList, const Color& currentColor)
     {
-        return adoptRefWillBeNoop(new AnimatableShadow(shadowList, currentColor));
+        return new AnimatableShadow(shadowList, currentColor);
     }
     ShadowList* shadowList() const { return m_shadowList.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: