feat(i18n): implement xmb serializer

modules/angular2/test/i18n/xmb_serializer_spec.ts

@@ -0,0 +1,35 @@
+import {
+  AsyncTestCompleter,
+  beforeEach,
+  ddescribe,
+  describe,
+  expect,
+  iit,
+  inject,
+  it,
+  xdescribe,
+  xit
+} from 'angular2/testing_internal';
+
+import {Message, id} from 'angular2/src/i18n/message';
+import {serialize} from 'angular2/src/i18n/xmb_serializer';
+
+export function main() {
+  describe('Xmb Serialization', () => {
+    it("should return an empty message bundle for an empty list of messages",
+       () => { expect(serialize([])).toEqual("<message-bundle></message-bundle>"); });
+
+    it("should serialize messages without desc", () => {
+      let m = new Message("content", "meaning", null);
+      let expected = `<message-bundle><msg id='${id(m)}'>content</msg></message-bundle>`;
+      expect(serialize([m])).toEqual(expected);
+    });
+
+    it("should serialize messages with desc", () => {
+      let m = new Message("content", "meaning", "description");
+      let expected =
+          `<message-bundle><msg id='${id(m)}' desc='description'>content</msg></message-bundle>`;
+      expect(serialize([m])).toEqual(expected);
+    });
+  });
+}