Generate dart2js and analyzer files for shared messages.

pkg/dart_messages/test/dart_messages_test.dart

Index: pkg/dart_messages/test/dart_messages_test.dart
diff --git a/pkg/dart_messages/test/dart_messages_test.dart b/pkg/dart_messages/test/dart_messages_test.dart
index 3983773b88f2c23ebc465742e51dea7adc8d6c89..274d941e564f1b7f0de9d41b7ee4c594d1525e83 100644
--- a/pkg/dart_messages/test/dart_messages_test.dart
+++ b/pkg/dart_messages/test/dart_messages_test.dart
@@ -16,10 +16,10 @@ void testJsonIsUpdated() {
       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";
   }
 }
@@ -27,7 +27,7 @@ void testJsonIsUpdated() {
 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";
     }