Sky: Add a DartConverterEnum and use that for all our enum needs.

sky/engine/core/painting/PaintingStyle.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 "sky/engine/config.h"
-#include "sky/engine/core/painting/PaintingStyle.h"
-
-#include "sky/engine/core/script/dom_dart_state.h"
-#include "sky/engine/tonic/dart_builtin.h"
-#include "sky/engine/tonic/dart_error.h"
-#include "sky/engine/tonic/dart_value.h"
-
-namespace blink {
-
-// If this fails, it's because SkXfermode has changed. We need to change
-// PaintingStyle.dart to ensure the PaintingStyle enum is in sync with the C++
-// values.
-COMPILE_ASSERT(SkPaint::kStyleCount == 3, Need_to_update_PaintingStyle_dart);
-
-// Convert dart_style => SkPaint::Style.
-SkPaint::Style DartConverter<PaintingStyle>::FromArgumentsWithNullCheck(
-    Dart_NativeArguments args,
-    int index,
-    Dart_Handle& exception) {
-  SkPaint::Style result;
-
-  Dart_Handle dart_style = Dart_GetNativeArgument(args, index);
-  DCHECK(!LogIfError(dart_style));
-
-  Dart_Handle value =
-      Dart_GetField(dart_style, DOMDartState::Current()->index_handle());
-
-  uint64_t style = 0;
-  Dart_Handle rv = Dart_IntegerToUint64(value, &style);
-  DCHECK(!LogIfError(rv));
-
-  result = static_cast<SkPaint::Style>(style);
-  return result;
-}
-
-} // namespace blink