Remove usage of dart:json.

pkg/intl/test/message_extraction/generate_from_json.dart

 #!/usr/bin/env dart
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * A main program that takes as input a source Dart file and a number
  * of JSON files representing translations of messages from the corresponding
  * Dart file. See extract_to_json.dart and make_hardcoded_translation.dart.
  *
  * This produces a series of files named
  * "messages_<locale>.dart" containing messages for a particular locale
  * and a main import file named "messages_all.dart" which has imports all of
  * them and provides an initializeMessages function.
  */
 library generate_from_json;
 
+import 'dart:convert';
 import 'dart:io';
 import 'package:intl/extract_messages.dart';
 import 'package:intl/src/intl_message.dart';
 import 'package:intl/generate_localized.dart';
-import 'dart:json' as json;
 import 'package:path/path.dart' as path;
 import 'package:args/args.dart';
 import 'package:serialization/serialization.dart';
 
 /**
  * Keeps track of all the messages we have processed so far, keyed by message
  * name.
  */
 Map<String, MainMessage> messages;
 
@@ skipping 51 matching lines @@
 }
 
 /**
  * Create the file of generated code for a particular locale. We read the json
  * data and create [BasicTranslatedMessage] instances from everything,
  * excluding only the special _locale attribute that we use to indicate the
  * locale.
  */
 void generateLocaleFile(File file, String targetDir) {
   var src = file.readAsStringSync();
-  var data = json.parse(src);
+  var data = JSON.decode(src);
   data.forEach((k, v) => data[k] = recreateIntlObjects(k, v));
   var locale = data["_locale"].string;
   allLocales.add(locale);
 
   var translations = [];
   data.forEach((key, value) {
     if (key[0] != "_") {
       translations.add(new BasicTranslatedMessage(key, value));
     }
   });
   generateIndividualMessageFile(locale, translations, targetDir);
 }
 
 /**
  * A TranslatedMessage that just uses the name as the id and knows how to look
  * up its original message in our [messages].
  */
 class BasicTranslatedMessage extends TranslatedMessage {
   BasicTranslatedMessage(String name, translated) :
       super(name, translated);
 
   MainMessage get originalMessage =>
       (super.originalMessage == null) ? _findOriginal() : super.originalMessage;
 
   // We know that our [id] is the name of the message, which is used as the
   //key in [messages].
   MainMessage _findOriginal() => originalMessage = messages[id];
 }