Speed up CompoundBindings

pkg/observe/test/list_change_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';
 
 // This file contains code ported from:
@@ skipping 58 matching lines @@
 
       // apply deltas to the copy
       for (var delta in summary) {
         copy.removeRange(delta.index, delta.index + delta.removedCount);
         for (int i = delta.addedCount - 1; i >= 0; i--) {
           copy.insert(delta.index, model[delta.index + i]);
         }
       }
 
       // Note: compare strings for easier debugging.
-      expect('$copy', '$model', reason: '!!! summary $summary');
+      expect('$copy', '$model', reason: 'summary $summary');
     }
 
     observeTest('Contained', () {
       var model = toObservable(['a', 'b']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeAt(1);
       model.insertAll(0, ['c', 'd', 'e']);
       model.removeRange(1, 3);
@@ skipping 195 matching lines @@
       model.insert(0, 5);
       model[2] = 6;
       model.add(7);
       assertEditDistance(model, 4);
     });
   });
 }
 
 _delta(i, r, a) => new ListChangeRecord(i, removedCount: r, addedCount: a);
 _filter(records) => records.where((r) => r is ListChangeRecord).toList();