Web Animations: Remove confusing interpolation subdirectory.

Source/core/animation/interpolation/StyleInterpolation.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 StyleInterpolation_h
-#define StyleInterpolation_h
-
-#include "core/CSSPropertyNames.h"
-#include "core/animation/interpolation/Interpolation.h"
-
-namespace blink {
-
-class StyleResolverState;
-
-class StyleInterpolation : public Interpolation {
-public:
-    // 1) convert m_cachedValue into an X
-    // 2) shove X into StyleResolverState
-    // X can be:
-    // (1) a CSSValue (and applied via StyleBuilder::applyProperty)
-    // (2) an AnimatableValue (and applied via // AnimatedStyleBuilder::applyProperty)
-    // (3) a custom value that is inserted directly into the StyleResolverState.
-    virtual void apply(StyleResolverState&) const = 0;
-
-    virtual bool isStyleInterpolation() const OVERRIDE FINAL { return true; }
-
-    CSSPropertyID id() const { return m_id; }
-
-    virtual void trace(Visitor* visitor) OVERRIDE
-    {
-        Interpolation::trace(visitor);
-    }
-
-protected:
-    CSSPropertyID m_id;
-
-    StyleInterpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> start, PassOwnPtrWillBeRawPtr<InterpolableValue> end, CSSPropertyID id)
-        : Interpolation(start, end)
-        , m_id(id)
-    {
-    }
-};
-
-DEFINE_TYPE_CASTS(StyleInterpolation, Interpolation, value, value->isStyleInterpolation(), value.isStyleInterpolation());
-
-}
-
-#endif