Web Animations: Remove confusing interpolation subdirectory.

Source/core/animation/interpolation/Interpolation.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 Interpolation_h
-#define Interpolation_h
-
-#include "core/animation/InterpolableValue.h"
-#include "platform/heap/Handle.h"
-
-namespace blink {
-
-class Interpolation : public RefCountedWillBeGarbageCollected<Interpolation> {
-    DECLARE_EMPTY_VIRTUAL_DESTRUCTOR_WILL_BE_REMOVED(Interpolation);
-public:
-    static PassRefPtrWillBeRawPtr<Interpolation> create(PassOwnPtrWillBeRawPtr<InterpolableValue> start, PassOwnPtrWillBeRawPtr<InterpolableValue> end)
-    {
-        return adoptRefWillBeNoop(new Interpolation(start, end));
-    }
-
-    void interpolate(int iteration, double fraction) const;
-
-    virtual bool isStyleInterpolation() const { return false; }
-    virtual bool isLegacyStyleInterpolation() const { return false; }
-
-    virtual void trace(Visitor*);
-
-protected:
-    const OwnPtrWillBeMember<InterpolableValue> m_start;
-    const OwnPtrWillBeMember<InterpolableValue> m_end;
-
-    mutable double m_cachedFraction;
-    mutable int m_cachedIteration;
-    mutable OwnPtrWillBeMember<InterpolableValue> m_cachedValue;
-
-    Interpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> start, PassOwnPtrWillBeRawPtr<InterpolableValue> end);
-
-private:
-    InterpolableValue* getCachedValueForTesting() const { return m_cachedValue.get(); }
-
-    friend class AnimationInterpolableValueTest;
-    friend class AnimationInterpolationEffectTest;
-};
-
-}
-
-#endif