[Oilpan]: Make StylePropertySet fully garbage collected.

Source/core/animation/InterpolationTest.cpp

 // Copyright 2014 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.
 
 #include "config.h"
 #include "core/animation/Interpolation.h"
 
 #include "core/css/CSSPrimitiveValue.h"
 #include "core/css/StylePropertySet.h"
 
@@ skipping 45 matching lines @@
     void initLengthArray(CSSLengthArray& lengthArray)
     {
         lengthArray.resize(CSSPrimitiveValue::LengthUnitTypeCount);
         for (size_t i = 0; i < CSSPrimitiveValue::LengthUnitTypeCount; ++i)
             lengthArray.at(i) = 0;
     }
 
     CSSLengthArray& setLengthArray(CSSLengthArray& lengthArray, String text)
     {
         initLengthArray(lengthArray);
-        RefPtr<MutableStylePropertySet> propertySet = MutableStylePropertySet::create();
+        RefPtrWillBeRawPtr<MutableStylePropertySet> propertySet = MutableStylePropertySet::create();
         propertySet->setProperty(CSSPropertyLeft, text);
         toCSSPrimitiveValue(propertySet->getPropertyCSSValue(CSSPropertyLeft).get())->accumulateLengthArray(lengthArray);
         return lengthArray;
     }
 
     bool lengthArraysEqual(CSSLengthArray& a, CSSLengthArray& b)
     {
         for (size_t i = 0; i < CSSPrimitiveValue::LengthUnitTypeCount; ++i) {
             if (a.at(i) != b.at(i))
                 return false;
@@ skipping 23 matching lines @@
 TEST_F(AnimationInterpolationTest, MultipleUnits)
 {
     CSSLengthArray actual, expectation;
     initLengthArray(expectation);
     OwnPtrWillBeRawPtr<InterpolableList> list = createInterpolableLength(0, 10, 0, 10, 0, 10, 0, 10, 0, 10);
     toCSSPrimitiveValue(interpolableValueToLength(list.get()).get())->accumulateLengthArray(expectation);
     EXPECT_TRUE(lengthArraysEqual(expectation, setLengthArray(actual, "calc(10%% + 10ex + 10ch + 10vh + 10vmax)")));
 }
 
 }