Oilpan: Remove most WillBe types from the code base

third_party/WebKit/Source/core/animation/LengthBoxStyleInterpolation.h

 // 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.
 
 #ifndef LengthBoxStyleInterpolation_h
 #define LengthBoxStyleInterpolation_h
 
 #include "core/CoreExport.h"
 #include "core/animation/LengthStyleInterpolation.h"
 #include "core/css/CSSBorderImageSliceValue.h"
 
 namespace blink {
 
 class CORE_EXPORT LengthBoxStyleInterpolation : public StyleInterpolation {
 public:
     static PassRefPtr<LengthBoxStyleInterpolation> maybeCreateFrom(CSSValue&, CSSValue&, CSSPropertyID);
 
     static bool usesDefaultInterpolation(const CSSValue&, const CSSValue&);
 
     void apply(StyleResolverState&) const override;
 
 private:
     LengthBoxStyleInterpolation(PassOwnPtr<InterpolableValue> startInterpolation, PassOwnPtr<InterpolableValue> endInterpolation, CSSPropertyID id, CSSValue* startCSS, CSSValue* endCSS)
         : StyleInterpolation(std::move(startInterpolation), std::move(endInterpolation), id)
         , m_startCSSValue(startCSS)
         , m_endCSSValue(endCSS)
     { }
 
     static PassOwnPtr<InterpolableValue> lengthBoxtoInterpolableValue(const CSSValue&, const CSSValue&, bool);
-    static PassRefPtrWillBeRawPtr<CSSValue> interpolableValueToLengthBox(InterpolableValue*, const CSSValue&, const CSSValue&);
+    static RawPtr<CSSValue> interpolableValueToLengthBox(InterpolableValue*, const CSSValue&, const CSSValue&);
 
-    RefPtrWillBePersistent<CSSValue> m_startCSSValue;
-    RefPtrWillBePersistent<CSSValue> m_endCSSValue;
+    Persistent<CSSValue> m_startCSSValue;
+    Persistent<CSSValue> m_endCSSValue;
 
     friend class AnimationLengthBoxStyleInterpolationTest;
 };
 
 } // namespace blink
 
 #endif // LengthBoxStyleInterpolation_h