fix observe tests

pkg/observe/test/observable_list_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:observe/observe.dart';
 import 'package:unittest/unittest.dart';
 import 'observe_test_utils.dart';
 
 main() {
@@ skipping 64 matching lines @@
 
     observeTest('clear changes length', () {
       list.clear();
       expect(list, []);
       performMicrotaskCheckpoint();
       expectChanges(changes, [_lengthChange(3, 0)]);
     });
   });
 
   group('observe index', () {
-    List<ChangeRecord> changes;
+    List<ListChangeRecord> changes;
 
     setUp(() {
       list = toObservable([1, 2, 3]);
       changes = null;
       sub = list.listChanges.listen((records) {
         changes = getListChangeRecords(records, 1);
       });
     });
 
     tearDown(sharedTearDown);
@@ skipping 62 matching lines @@
     });
   });
 
   observeTest('toString', () {
     var list = toObservable([1, 2, 3]);
     expect(list.toString(), '[1, 2, 3]');
   });
 
   group('change records', () {
 
-    List<PropertyChangeRecord> propRecords;
+    List<ChangeRecord> propRecords;
     List<ListChangeRecord> listRecords;
 
     setUp(() {
       list = toObservable([1, 2, 3, 1, 3, 4]);
       propRecords = null;
       listRecords = null;
       sub = list.changes.listen((r) { propRecords = r; });
       sub2 = list.listChanges.listen((r) { listRecords = r; });
     });
 
@@ skipping 80 matching lines @@
   });
 }
 
 ObservableList list;
 
 _lengthChange(int oldValue, int newValue) =>
     new PropertyChangeRecord(list, #length, oldValue, newValue);
 
 _change(index, {removed: const [], addedCount: 0}) => new ListChangeRecord(
     list, index, removed: removed, addedCount: addedCount);