Roll Observatory packages and add a roll script

packages/observe/benchmark/setup_object_benchmark.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.benchmark.setup_object_benchmark;
+
+import 'setup_observation_benchmark_base.dart';
+import 'test_observable.dart';
+
+class SetupObjectBenchmark extends SetupObservationBenchmarkBase {
+  SetupObjectBenchmark(int objectCount, String config)
+      : super('SetupObjectBenchmark:$objectCount:$config', objectCount, config);
+
+  @override
+  TestObservable newObject() => new TestObservable();
+}