pkg: analysis aided cleanup

pkg/scheduled_test/test/scheduled_test/simple_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 'dart:io';
 
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../metatest.dart';
 import '../utils.dart';
 
 void main() {
   setUpTimeout();
 
   expectTestsPass('a scheduled test with a correct synchronous expectation '
@@ skipping 97 matching lines @@
 
   expectTestsFail('an error in a chained future in a scheduled block should be '
       'registered', () {
     test('test', () {
       schedule(() => new Future.value().then((_) {
         throw 'error';
       }));
     });
   });
 }