Modernize the package's style.

test/utils.dart

 // Copyright (c) 2015, 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.
 
 /// Helper utilities for testing.
-library async.test.util;
-
 import "dart:async";
 
 import "package:async/async.dart";
 import "package:test/test.dart";
 
 /// A zero-millisecond timer should wait until after all microtasks.
 Future flushMicrotasks() => new Future.delayed(Duration.ZERO);
 
 /// A generic unreachable callback function.
 ///
@@ skipping 60 matching lines @@
     stream.listen(add, onError: addError, onDone: completer.complete);
     return completer.future;
   }
 
   Future close() {
     _isClosed = true;
     _doneCompleter.complete(new Future.microtask(_onDone));
     return done;
   }
 }