Add async initialization for Intl.message and an example

pkg/intl/test/intl_test.dart

Index: pkg/intl/test/intl_test.dart
===================================================================
--- pkg/intl/test/intl_test.dart	(revision 12343)
+++ pkg/intl/test/intl_test.dart	(working copy)
@@ -5,17 +5,24 @@
 #library('intl_test');
 
 #import('../intl.dart');
-#import('../../../pkg/unittest/unittest.dart');
+#import('../../unittest/unittest.dart');
 #import('../date_symbol_data_local.dart');
 
 main() {
-  test('Set locale', (){
+  test("Locale setting doesn't verify the core locale", () {
+      var de = new Intl('de_DE');
+      expect(de.locale, equals('de_DE'));
+  });
+
+  test('DateFormat creation does verify the locale', (){
     // TODO(alanknight): We need to make the locale verification be on a per
     // usage basis rather than once for the entire Intl object. The set of
     // locales covered for messages may be different from that for date
     // formatting.
     initializeDateFormatting('de_DE', null).then((_) {
       var de = new Intl('de_DE');
-      expect(de.locale, equals('de'));});
+      var format = de.date().add_d();
+      expect(format.locale, equals('de'));
+     });
   });
 }