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

Source/core/animation/ImageSliceStyleInterpolation.h

Index: Source/core/animation/ImageSliceStyleInterpolation.h
diff --git a/Source/core/animation/ImageSliceStyleInterpolation.h b/Source/core/animation/ImageSliceStyleInterpolation.h
index 46f56612bc55e3da13c17f7e4a5f2434b67ce741..7305640869c75f3ed40cae15e18ee0196ce8e7a3 100644
--- a/Source/core/animation/ImageSliceStyleInterpolation.h
+++ b/Source/core/animation/ImageSliceStyleInterpolation.h
@@ -14,7 +14,7 @@ class CSSBorderImageSliceValue;
 class ImageSliceStyleInterpolation : public StyleInterpolation {
 public:
     static bool usesDefaultInterpolation(const CSSValue&, const CSSValue&);
-    static PassRefPtrWillBeRawPtr<ImageSliceStyleInterpolation> maybeCreate(const CSSValue&, const CSSValue&, CSSPropertyID);
+    static ImageSliceStyleInterpolation* maybeCreate(const CSSValue&, const CSSValue&, CSSPropertyID);
 
     void apply(StyleResolverState&) const override;
     DECLARE_VIRTUAL_TRACE();
@@ -27,7 +27,7 @@ public:
     };
 
 private:
-    ImageSliceStyleInterpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> start, PassOwnPtrWillBeRawPtr<InterpolableValue> end, CSSPropertyID property, Metadata metadata)
+    ImageSliceStyleInterpolation(InterpolableValue* start, InterpolableValue* end, CSSPropertyID property, Metadata metadata)
         : StyleInterpolation(start, end, property)
         , m_metadata(metadata)
     { }