pkg: analysis aided cleanup

pkg/scheduled_test/test/descriptor/nothing_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:path/path.dart' as path;
 import 'package:scheduled_test/descriptor.dart' as d;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../metatest.dart';
 import 'utils.dart';
 
 void main() {
@@ skipping 62 matching lines @@
 
     test('test 2', () {
       expect(errors, everyElement(new isInstanceOf<ScheduleError>()));
       expect(errors.length, equals(1));
       expect(errors.first.error,
           matches(r"^Expected nothing to exist at '[^']+[\\/]dir', but found a "
               r"directory\.$"));
     });
   }, passing: ['test 2']);
 }