Fix a broken scheduled_test test.

pkg/scheduled_test/test/scheduled_test/nested_task_test.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.
 
 import 'dart:async';
 
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/src/mock_clock.dart' as mock_clock;
 
 import '../metatest.dart';
@@ skipping 72 matching lines @@
     });
 
     test('test 2', () {
       expect(errors, everyElement(new isInstanceOf<ScheduleError>()));
       expect(errors.map((e) => e.error), equals(['error']));
     });
   }, passing: ['test 2']);
 
   expectTestsPass("nested scheduled blocks whose return values are passed to "
       "wrapFuture should report exceptions once", () {
-    var error = new Object();
+    var error = 'oh no!';
     var errors;
     test('test 1', () {
       currentSchedule.onException.schedule(() {
         errors = currentSchedule.errors;
       });
 
       schedule(() {
         wrapFuture(schedule(() {
           throw error;
         }));
@@ skipping 26 matching lines @@
           parentTaskFinished = true;
         });
       });
     });
 
     test('test 2', () {
       expect(parentTaskFinishedBeforeOnComplete, isTrue);
     });
   }, passing: ['test 2']);
 }