anchor.diff:  //
   // If you create classes that are referenced from the Angular
   // expressions, you must include a library target in @MirrorsUsed.
  -@MirrorsUsed(override: '*')
  +@MirrorsUsed(
  +    targets: const [ 'Item' ],
  +    override: '*')
   import 'dart:mirrors';
   
   class Item {
  
positive.code: 
  // An implementation of ServerController that fetches items from
  // the server over HTTP.
  class HttpServerController implements ServerController {
    final Http _http;
    HttpServerController(this._http);
  
negative.code: 
  
  // An implementation of ServerController that does nothing.
  @NgInjectableService()
  class NoServerController implements ServerController {
    init(TodoController todo) { }
  }
  