Web Animations: Remove confusing interpolation subdirectory.

Source/core/animation/interpolation/LegacyStyleInterpolation.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 LegacyStyleInterpolation_h
-#define LegacyStyleInterpolation_h
-
-#include "core/animation/interpolation/StyleInterpolation.h"
-#include "core/css/resolver/AnimatedStyleBuilder.h"
-
-namespace blink {
-
-class LegacyStyleInterpolation : public StyleInterpolation {
-public:
-    static PassRefPtrWillBeRawPtr<LegacyStyleInterpolation> create(PassRefPtrWillBeRawPtr<AnimatableValue> start, PassRefPtrWillBeRawPtr<AnimatableValue> end, CSSPropertyID id)
-    {
-        return adoptRefWillBeNoop(new LegacyStyleInterpolation(InterpolableAnimatableValue::create(start), InterpolableAnimatableValue::create(end), id));
-    }
-
-    virtual void apply(StyleResolverState& state) const OVERRIDE
-    {
-        AnimatedStyleBuilder::applyProperty(m_id, state, currentValue().get());
-    }
-
-    virtual bool isLegacyStyleInterpolation() const OVERRIDE FINAL { return true; }
-    PassRefPtrWillBeRawPtr<AnimatableValue> currentValue() const
-    {
-        return toInterpolableAnimatableValue(m_cachedValue.get())->value();
-    }
-
-    virtual void trace(Visitor* visitor) OVERRIDE
-    {
-        StyleInterpolation::trace(visitor);
-    }
-
-private:
-    LegacyStyleInterpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> start, PassOwnPtrWillBeRawPtr<InterpolableValue> end, CSSPropertyID id)
-        : StyleInterpolation(start, end, id)
-    {
-    }
-};
-
-DEFINE_TYPE_CASTS(LegacyStyleInterpolation, Interpolation, value, value->isLegacyStyleInterpolation(), value.isLegacyStyleInterpolation());
-
-}
-
-#endif