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

Source/core/animation/LengthPairStyleInterpolationTest.cpp

Index: Source/core/animation/LengthPairStyleInterpolationTest.cpp
diff --git a/Source/core/animation/LengthPairStyleInterpolationTest.cpp b/Source/core/animation/LengthPairStyleInterpolationTest.cpp
index e2cef4f9a2658231eb68cbcbc9b85d2008a22be9..9b64af45908d708f21dd9efd7d647268a30b823d 100644
--- a/Source/core/animation/LengthPairStyleInterpolationTest.cpp
+++ b/Source/core/animation/LengthPairStyleInterpolationTest.cpp
@@ -17,7 +17,7 @@ namespace blink {
 class LengthPairStyleInterpolationTest : public ::testing::Test {
 
 protected:
-    static PassOwnPtrWillBeRawPtr<InterpolableValue> lengthPairToInterpolableValue(const CSSValue& value)
+    static InterpolableValue* lengthPairToInterpolableValue(const CSSValue& value)
     {
         return LengthPairStyleInterpolation::lengthPairToInterpolableValue(value);
     }
@@ -29,7 +29,7 @@ protected:
 
     static PassRefPtrWillBeRawPtr<CSSValue> roundTrip(PassRefPtrWillBeRawPtr<CSSValue> value, InterpolationRange range)
     {
-        return interpolableValueToLengthPair(lengthPairToInterpolableValue(*value).get(), range);
+        return interpolableValueToLengthPair(lengthPairToInterpolableValue(*value), range);
     }
 
     static void testPrimitiveValue(RefPtrWillBeRawPtr<CSSValue> value, double first, double second, CSSPrimitiveValue::UnitType unitType)