Add smooth interpolation support for <color> custom properties

third_party/WebKit/Source/core/animation/CSSColorInterpolationType.cpp

 // 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.
 
 #include "core/animation/CSSColorInterpolationType.h"
 
 #include "core/animation/ColorPropertyFunctions.h"
 #include "core/css/CSSColorValue.h"
 #include "core/css/CSSIdentifierValue.h"
 #include "core/css/resolver/StyleResolverState.h"
@@ skipping 247 matching lines @@
       resolveInterpolableColor(
           *colorPair.get(Unvisited), state, false,
           cssProperty() == CSSPropertyTextDecorationColor));
   ColorPropertyFunctions::setVisitedColor(
       cssProperty(), *state.style(),
       resolveInterpolableColor(
           *colorPair.get(Visited), state, true,
           cssProperty() == CSSPropertyTextDecorationColor));
 }
 
+const CSSValue* CSSColorInterpolationType::createCSSValue(
+    const InterpolableValue& interpolableValue,
+    const NonInterpolableValue*,
+    const StyleResolverState& state) const {
+  const InterpolableList& colorPair = toInterpolableList(interpolableValue);
+  Color color = resolveInterpolableColor(*colorPair.get(Unvisited), state);
+  return CSSColorValue::create(color.rgb());
+}
+
 }  // namespace blink