fix observe package to be strong mode clean

test/observe_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 'package:logging/logging.dart';
 import 'package:observe/observe.dart';
 import 'package:observe/src/dirty_check.dart' as dirty_check;
 import 'observe_test_utils.dart';
 
@@ skipping 31 matching lines @@
     });
 
     tearDown(() {
       subscription.cancel();
     });
 
     test('logs debug information', () {
       var maxNumIterations = dirty_check.MAX_DIRTY_CHECK_CYCLES;
 
       var x = new WatcherModel(0);
-      var sub = x.changes.listen(expectAsync((_) {
+      int called = 0;
+      var sub = x.changes.listen((_) {
+        called++;
         x.value++;
-      }, count: maxNumIterations));
+      });
       x.value = 1;
       Observable.dirtyCheck();
+      expect(called, maxNumIterations);
       expect(x.value, maxNumIterations + 1);
       expect(messages.length, 2);
 
       expect(messages[0], contains('Possible loop'));
       expect(messages[1], contains('index 0'));
       expect(messages[1], contains('object: $x'));
 
       sub.cancel();
     });
   });
@@ skipping 123 matching lines @@
     t.value = 42;
   });
 
   test('cancel and reobserve', () {
     var t = createModel(123);
     var sub;
     sub = t.changes.listen(expectAsync((records) {
       expectPropertyChanges(records, 1);
       sub.cancel();
 
-      scheduleMicrotask(expectAsync(() {
+      scheduleMicrotask(() {
         subs.add(t.changes.listen(expectAsync((records) {
           expectPropertyChanges(records, 1);
         })));
         t.value = 777;
         scheduleMicrotask(Observable.dirtyCheck);
-      }));
+      });
     }));
     t.value = 42;
   });
 
   test('cannot modify changes list', () {
     var t = createModel(123);
     var records = null;
     subs.add(t.changes.listen((r) {
       records = r;
     }));
@@ skipping 63 matching lines @@
   @observable T value;
 
   WatcherModel([T initialValue]) : value = initialValue;
 
   String toString() => '#<$runtimeType value: $value>';
 }
 
 class ModelSubclass<T> extends WatcherModel<T> {
   ModelSubclass([T initialValue]) : super(initialValue);
 }