Add foundation for removing AnimatableValues from StyleInterpolation

Source/core/animation/AnimationType.h

Index: Source/core/animation/AnimationType.h
diff --git a/Source/core/animation/AnimationType.h b/Source/core/animation/AnimationType.h
new file mode 100644
index 0000000000000000000000000000000000000000..5e65eebb598d1f4e83cf69f390d02cca2b84e0a6
--- /dev/null
+++ b/Source/core/animation/AnimationType.h
@@ -0,0 +1,51 @@
+// Copyright 2015 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 AnimationType_h
+#define AnimationType_h
+
+#include "core/animation/InterpolableValue.h"
+#include "core/animation/InterpolationInvalidators.h"
+#include "core/animation/NonInterpolableValue.h"
+#include "core/animation/StringKeyframe.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class StyleResolverState;
+struct AnimationValue;
+class InterpolableValue;
+
+class AnimationType {
+public:
+    virtual CSSPropertyID property() const = 0;
+
+    virtual bool maybeConvertPairwise(
+        const CSSPropertySpecificKeyframe& startKeyframe,
+        const CSSPropertySpecificKeyframe& endKeyframe,
+        const StyleResolverState*,
+        RefPtrWillBeRawPtr<InterpolationInvalidators>& resultInvalidators,
+        OwnPtrWillBeRawPtr<InterpolableValue>& resultStartInterpolableValue,
+        OwnPtrWillBeRawPtr<InterpolableValue>& resultEndInterpolableValue,
+        RefPtrWillBeRawPtr<NonInterpolableValue>& resultNonInterpolableValue) const
+    {
+        return false;

[shans, 2015/05/28 05:48:13]

Shouldn't the default implementation of this attempt two single conversions?

[alancutter (OOO until 2018), 2015/06/01 07:35:28]

Yes. DefaultAnimationType does not make use of it at the moment so I left it out
of this patch.

+    }
+
+    virtual bool maybeConvertSingle(
+        const CSSPropertySpecificKeyframe&,
+        const StyleResolverState*,
+        RefPtrWillBeRawPtr<InterpolationInvalidators>& resultInvalidators,
+        OwnPtrWillBeRawPtr<InterpolableValue>& resultInterpolableValue,
+        RefPtrWillBeRawPtr<NonInterpolableValue>& resultNonInterpolableValue) const
+    {
+        return false;
+    }
+
+    virtual void apply(const InterpolableValue&, const NonInterpolableValue*, StyleResolverState&) const = 0;
+};
+
+} // namespace blink
+
+#endif // AnimationType_h