Change MatchState to Map.

pkg/scheduled_test/lib/src/scheduled_future_matchers.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 scheduled_future_matchers;
 
 import 'dart:async';
 
 import 'package:stack_trace/stack_trace.dart';
 
@@ skipping 28 matching lines @@
 /// the [expect]'s error message.
 Matcher completion(matcher, [String description]) =>
     new _ScheduledCompletes(wrapMatcher(matcher), description);
 
 class _ScheduledCompletes extends BaseMatcher {
   final Matcher _matcher;
   final String _description;
 
   const _ScheduledCompletes(this._matcher, this._description);
 
-  bool matches(item, MatchState matchState) {
+  bool matches(item, Map matchState) {
     if (item is! Future) return false;
 
     // TODO(nweiz): parse the stack, figure out on what line these were called,
     // and include that in their descriptions
     var description = _description;
     if (description == null) {
       if (_matcher == null) {
         description = 'expect(..., completes)';
       } else {
         var matcherDescription = new StringDescription();
@@ skipping 17 matching lines @@
 
   Description describe(Description description) {
     if (_matcher == null) {
       description.add('completes successfully');
     } else {
       description.add('completes to a value that ').addDescriptionOf(_matcher);
     }
     return description;
   }
 }