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

Source/core/animation/ImageSliceStyleInterpolation.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ImageSliceStyleInterpolation_h
 #define ImageSliceStyleInterpolation_h
 
 #include "core/animation/StyleInterpolation.h"
 
 namespace blink {
 
 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();
 
     // Image slices can have either percentages or numbers: http://dev.w3.org/csswg/css-backgrounds-3/#the-border-image-slice
     struct Metadata {
         bool isPercentage;
         bool fill;
         bool operator==(const Metadata& o) const { return isPercentage == o.isPercentage && fill == o.fill; }
     };
 
 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)
     { }
 
     Metadata m_metadata;
 };
 
 } // namespace blink
 
 #endif // ImageSliceStyleInterpolation_h