Roll Observatory packages and add a roll script

packages/observe/test/observe_test_utils.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 observe.test.observe_test_utils;
+
+import 'dart:async';
+import 'package:observe/observe.dart';
+import 'package:observe/mirrors_used.dart'; // to make tests smaller
+import 'package:unittest/unittest.dart';
+export 'package:observe/src/dirty_check.dart' show dirtyCheckZone;
+
+/// A small method to help readability. Used to cause the next "then" in a chain
+/// to happen in the next microtask:
+///
+///     future.then(newMicrotask).then(...)
+newMicrotask(_) => new Future.value();
+
+// TODO(jmesserly): use matchers when we have a way to compare ChangeRecords.
+// For now just use the toString.
+expectChanges(actual, expected, {reason}) =>
+    expect('$actual', '$expected', reason: reason);
+
+List getListChangeRecords(List changes, int index) => changes
+    .where((c) => c.indexChanged(index)).toList();
+
+List getPropertyChangeRecords(List changes, Symbol property) => changes
+    .where((c) => c is PropertyChangeRecord && c.name == property).toList();