Split the CSSParserContext class out of CSSParserMode into its own file.

third_party/WebKit/Source/web/WebCSSParser.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 "public/web/WebCSSParser.h"
 
 #include "core/css/parser/CSSParser.h"
+#include "platform/graphics/Color.h"
 #include "public/platform/WebString.h"
 
 namespace blink {
 
 bool WebCSSParser::parseColor(WebColor* webColor,
                               const WebString& colorString) {
   Color color = Color(*webColor);
   bool success = CSSParser::parseColor(color, colorString, true);
   *webColor = color.rgb();
   return success;
 }
 
 }  // namespace blink