Generate dart2js and analyzer files for shared messages.

pkg/dart_messages/test/dart_messages_test.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:convert';
 import 'dart:io';
 
 import '../lib/shared_messages.dart';
 
 void testJsonIsUpdated() {
   var packageRoot = Platform.packageRoot;
   if (packageRoot == null || packageRoot == "") {
     throw new UnsupportedError("This test requires a package root.");
   }
   var jsonUri =
       Uri.parse(packageRoot).resolve('dart_messages/shared_messages.json');
   var jsonPath = jsonUri.toFilePath();
   var content = new File(jsonPath).readAsStringSync();
-  if (JSON.encode(MESSAGES) != content) {
+  if (messagesAsJson != content) {
     print("The content of the Dart messages and the corresponding JSON file");
     print("is not the same.");
-    print("Please run bin/json_converter to update the JSON file.");
+    print("Please run bin/publish.dart to update the JSON file.");
     throw "Content is not the same";
   }
 }
 
 void testIdsAreUnique() {
   var usedIds = new Set();
   for (var entry in MESSAGES.values) {
-    var id = entry['id'];
+    var id = entry.id;
     if (!usedIds.add(id)) {
       throw "Id appears twice: $id";
     }
   }
 }
 
 void main() {
   testJsonIsUpdated();
   testIdsAreUnique();
 }