refactor(i18n): move message and id into a separate file

modules/angular2/test/i18n/message_extractor_spec.ts

@@ -12,7 +12,8 @@ import {
 } from 'angular2/testing_internal';
 
 import {HtmlParser} from 'angular2/src/compiler/html_parser';
-import {MessageExtractor, Message, removeDuplicates} from 'angular2/src/i18n/message_extractor';
+import {MessageExtractor, removeDuplicates} from 'angular2/src/i18n/message_extractor';
+import {Message} from 'angular2/src/i18n/message';
 import {Parser} from 'angular2/src/core/change_detection/parser/parser';
 import {Lexer} from 'angular2/src/core/change_detection/parser/lexer';
 

modules/angular2/test/i18n/message_spec.ts

@@ -0,0 +1,27 @@
+import {
+  AsyncTestCompleter,
+  beforeEach,
+  ddescribe,
+  describe,
+  expect,
+  iit,
+  inject,
+  it,
+  xdescribe,
+  xit
+} from 'angular2/testing_internal';
+
+import {Message, id} from 'angular2/src/i18n/message';
+
+export function main() {
+  ddescribe('Message', () => {
+    describe("id", () => {
+      it("should return a different id for messages with and without the meaning", () => {
+        let m1 = new Message("content", "meaning", null);
+        let m2 = new Message("content", null, null);
+        expect(id(m1)).toEqual(id(m1));
+        expect(id(m1)).not.toEqual(id(m2));
+      });
+    });
+  });
+}