Roll Observatory packages and add a roll script

packages/unittest/test/middle_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.middle_exception_test;
+
+import 'dart:async';
+
+import 'package:metatest/metatest.dart';
+import 'package:unittest/unittest.dart';
+
+void main() => initTests(_test);
+
+void _test(message) {
+  initMetatest(message);
+
+  expectTestResults('late exception test', () {
+    test('testOne', () {
+      expect(true, isTrue);
+    });
+    test('testTwo', () {
+      expect(true, isFalse);
+    });
+    test('testThree', () {
+      var done = expectAsync(() {});
+      new Future.sync(() {
+        expect(true, isTrue);
+        done();
+      });
+    });
+  }, [{'result': 'pass'}, {'result': 'fail',}, {'result': 'pass'}]);
+}