anchor.diff:        this.printProcedure,
         this.completerConstructor,
         this.syncIterableConstructor,
  +      this.streamIteratorConstructor,
         this.futureMicrotaskConstructor,
         this.streamControllerConstructor,
         this.asyncThenWrapper,
  
positive.code:   final Procedure futureMicrotaskConstructor;
    final Constructor streamControllerConstructor;
    final Constructor syncIterableConstructor;
    final Procedure asyncThenWrapper;
    final Procedure asyncErrorWrapper;
    final Procedure awaitHelper;
  
negative.code: 
      var completerClass = findClass(asyncLibrary, 'Completer');
      var futureClass = findClass(asyncLibrary, 'Future');
      var streamIteratorClass = findClass(asyncLibrary, '_StreamIteratorImpl');
      var syncIterableClass = findClass(coreLibrary, '_SyncIterable');
      var streamControllerClass = findClass(
          asyncLibrary, '_AsyncStarStreamController');
  