Add async initialization for Intl.message and an example

pkg/intl/test/intl_message_test.dart

 // Copyright (c) 2012, 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.
 
-
 #library('intl_message_test');
 
 #import('../intl.dart');
-#import('../../../pkg/unittest/unittest.dart');
+#import('../../unittest/unittest.dart');
+#import('../message_lookup_local.dart');
 
 /** Tests the MessageFormat library in dart. */
 
 class Person {
   String firstName, lastName;
   Person(this.firstName, this.lastName);
 }
 
 main() {
+  initializeMessages('en_US').then(runTests);
+}
+
+runTests(_) {
   test('Trivial Message', () {
     hello() => Intl.message('Hello, world!',
         desc: 'hello world string');
     expect(hello(), equals('Hello, world!'));
   });
 
   test('Message with one parameter', () {
     lucky(number) => Intl.message('Your lucky number is $number',
         desc: 'number str', examples: {'number': 2});
     expect(lucky(3), equals('Your lucky number is 3'));
@@ skipping 48 matching lines @@
         desc: 'explains the locale');
     expect(Intl.withLocale('en-US', () => hello()), equals('locale=en-US'));
   });
 
   test('Test passing locale', () {
     hello(a_locale) => Intl.message('locale=${Intl.getCurrentLocale()}',
         desc: 'explains the locale', locale: a_locale);
     expect(hello('en-US'), equals('locale=en_US'));
   });
 }