Roll Observatory packages and add a roll script

packages/unittest/test/exception_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.
+
+library unittest.exception_test;
+
+import 'package:unittest/unittest.dart';
+
+import 'package:metatest/metatest.dart';
+
+void main() => initTests(_test);
+
+void _test(message) {
+  initMetatest(message);
+
+  expectTestResults('good setup/good teardown', () {
+    test('test', () {
+      throw new Exception('Fail.');
+    });
+  }, [{'result': 'error', 'message': 'Test failed: Caught Exception: Fail.'}]);
+}