Remove AsyncError with Expando.

pkg/scheduled_test/lib/src/schedule.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 schedule;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:stack_trace/stack_trace.dart';
@@ skipping 170 matching lines @@
       throw new StateError("Called abort() after the schedule has finished "
           "running.");
     }
 
     currentQueue._abort();
   }
 
   /// Signals that an out-of-band error has occurred. Using [wrapAsync] along
   /// with `throw` is usually preferable to calling this directly.
   ///
-  /// The metadata in [AsyncError]s and [ScheduleError]s will be preserved.
+  /// The metadata in [ScheduleError]s will be preserved.
   void signalError(error, [stackTrace]) {
     heartbeat();
 
     var scheduleError = new ScheduleError.from(this, error,
         stackTrace: stackTrace);
     if (_state == ScheduleState.DONE) {
       throw new StateError(
           "An out-of-band error was signaled outside of wrapAsync after the "
               "schedule finished running.\n"
           "${errorString()}");
@@ skipping 396 matching lines @@
           return prefixLines(childString,
               firstPrefix: "  $prefix ", prefix: "  | ");
         }).join('\n');
         taskString = '$taskString\n$childrenString';
       }
 
       return taskString;
     }).join("\n");
   }
 }