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

Source/core/animation/LengthInterpolationType.h

Index: Source/core/animation/LengthInterpolationType.h
diff --git a/Source/core/animation/LengthInterpolationType.h b/Source/core/animation/LengthInterpolationType.h
index c9f82fdbb7e48796c8d1579f9eb5b530073829bf..143dc8d6291443770e36623f7297eaa6924cad8d 100644
--- a/Source/core/animation/LengthInterpolationType.h
+++ b/Source/core/animation/LengthInterpolationType.h
@@ -14,15 +14,15 @@ class LengthInterpolationType : public InterpolationType {
 public:
     LengthInterpolationType(CSSPropertyID);
 
-    PassOwnPtrWillBeRawPtr<InterpolationValue> maybeConvertUnderlyingValue(const StyleResolverState&) const final;
+    InterpolationValue* maybeConvertUnderlyingValue(const StyleResolverState&) const final;
     void apply(const InterpolableValue&, const NonInterpolableValue*, StyleResolverState&) const final;
 
 private:
-    PassOwnPtrWillBeRawPtr<InterpolationValue> maybeConvertLength(const Length&, float zoom) const;
-    PassOwnPtrWillBeRawPtr<InterpolationValue> maybeConvertNeutral() const final;
-    PassOwnPtrWillBeRawPtr<InterpolationValue> maybeConvertInitial() const final;
-    PassOwnPtrWillBeRawPtr<InterpolationValue> maybeConvertInherit(const StyleResolverState*, ConversionCheckers&) const final;
-    PassOwnPtrWillBeRawPtr<InterpolationValue> maybeConvertValue(const CSSValue&, const StyleResolverState*, ConversionCheckers&) const final;
+    InterpolationValue* maybeConvertLength(const Length&, float zoom) const;
+    InterpolationValue* maybeConvertNeutral() const final;
+    InterpolationValue* maybeConvertInitial() const final;
+    InterpolationValue* maybeConvertInherit(const StyleResolverState*, ConversionCheckers&) const final;
+    InterpolationValue* maybeConvertValue(const CSSValue&, const StyleResolverState*, ConversionCheckers&) const final;
 
     const ValueRange m_valueRange;
 };