fix(dart): fix the static_browser platform not to include compiler

Closes #5321

modules/angular2/src/compiler/xhr.ts

@@ -1,6 +1,6 @@
 import {Promise} from 'angular2/src/facade/async';
 
-// TODO: vsavkin rename it into TemplateLoader and do not reexport it via DomAdapter
+// TODO: vsavkin rename it into TemplateLoader
 export class XHR {
   get(url: string): Promise<string> { return null; }
 }