Change the way Patterns work in scheduled_test/descriptor.

pkg/scheduled_test/lib/src/descriptor/async.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 descriptor.async;
-
-import 'dart:async';
-import 'dart:io' as io;
-
-import '../../descriptor.dart' as descriptor;
-import '../../scheduled_test.dart';
-import '../utils.dart';
-import 'utils.dart';
-
-/// A descriptor that wraps a [Future<Entry>] and forwards all asynchronous
-/// operations to the result of the future. It's designed for use when the
-/// full filesystem description isn't known when initializing the schedule.
-///
-/// Async descriptors don't support [load], since their names aren't
-/// synchronously available.
-class Async extends descriptor.Entry {
-  /// The [Future] that will complete to the [Entry] this descriptor is
-  /// wrapping.
-  final Future<descriptor.Entry> future;
-
-  Async(this.future)
-      : super('<async descriptor>');
-
-  Future create([String parent]) =>
-    schedule(() => future.then((entry) => entry.create(parent)));
-
-  Future validate([String parent]) =>
-    schedule(() => future.then((entry) => entry.validate(parent)));
-
-  Stream<List<int>> load(String path) => errorStream("Async descriptors don't "
-      "support load().");
-
-  Stream<List<int>> read() => errorStream("Async descriptors don't support "
-      "read().");
-
-  String describe() => "async descriptor";
-}