Remove AsyncError with Expando.

pkg/scheduled_test/lib/src/substitute_future.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library substitute_future;
 
 import 'dart:async';
 
 /// A wrapper for [Future] that allows other [Future]s to be substituted in as
 /// the wrapped [Future]. This is used for injecting timeout errors into
 /// long-running [Future]s.
 class SubstituteFuture<T> implements Future<T> {
   /// The wrapped [Future].
   Future<T> _inner;
 
   /// The completer that corresponds to [this]'s result.
   final Completer<T> _completer = new Completer<T>();
 
   /// Whether or not [this] has been completed yet.
   bool _complete = false;
 
   SubstituteFuture(Future wrapped) {
     substitute(wrapped);
   }
 
   Stream<T> asStream() => _completer.future.asStream();
-  Future catchError(onError(AsyncError asyncError), {bool test(error)}) =>
+  Future catchError(onError(asyncError), {bool test(error)}) =>
     _completer.future.catchError(onError, test: test);
-  Future then(onValue(T value), {onError(AsyncError asyncError)}) =>
+  Future then(onValue(T value), {onError(error)}) =>
     _completer.future.then(onValue, onError: onError);
   Future<T> whenComplete(action()) => _completer.future.whenComplete(action);
 
   /// Substitutes [newFuture] for the currently wrapped [Future], which is
   /// returned.
   Future<T> substitute(Future<T> newFuture) {
     if (_complete) {
       throw new StateError("You may not call substitute on a SubstituteFuture "
           "that's already complete.");
     }
 
     var oldFuture = _inner;
     _inner = newFuture;
     _inner.then((value) {
       if (_inner != newFuture) return;
       _completer.complete(value);
       _complete = true;
     }).catchError((error) {
       if (_inner != newFuture) return;
       _completer.completeError(error);
       _complete = true;
     });
     return oldFuture;
   }
 }