Remove AsyncError with Expando.

pkg/scheduled_test/lib/src/value_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 value_future;
 
 import 'dart:async';
 
 /// A [Future] wrapper that provides synchronous access to the value of the
 /// wrapped [Future] once it's completed.
@@ skipping 12 matching lines @@
 
   ValueFuture(Future<T> future) {
     _future = future.then((value) {
       _value = value;
       _hasValue = true;
       return value;
     });
   }
 
   Stream<T> asStream() => _future.asStream();
-  Future catchError(onError(AsyncError asyncError), {bool test(error)}) =>
+  Future catchError(onError(Object error), {bool test(error)}) =>
     _future.catchError(onError, test: test);
-  Future then(onValue(T value), {onError(AsyncError asyncError)}) =>
+  Future then(onValue(T value), {onError(Object error)}) =>
     _future.then(onValue, onError: onError);
   Future<T> whenComplete(action()) => _future.whenComplete(action);
 }