Re-apply "Remove unittest and matcher from the repo."

pkg/unittest/test/nested_groups_setup_teardown_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.nested_groups_setup_teardown_test;
-
-import 'dart:async';
-
-import 'package:unittest/unittest.dart';
-
-import 'package:metatest/metatest.dart';
-
-void main() => initTests(_test);
-
-void _test(message) {
-  initMetatest(message);
-
-  expectTestsPass('nested groups setup/teardown', () {
-    StringBuffer s = new StringBuffer();
-    group('level 1', () {
-      setUp(makeDelayedSetup(1, s));
-      group('level 2', () {
-        setUp(makeImmediateSetup(2, s));
-        tearDown(makeDelayedTeardown(2, s));
-        group('level 3', () {
-          group('level 4', () {
-            setUp(makeDelayedSetup(4, s));
-            tearDown(makeImmediateTeardown(4, s));
-            group('level 5', () {
-              setUp(makeImmediateSetup(5, s));
-              group('level 6', () {
-                tearDown(makeDelayedTeardown(6, s));
-                test('inner', () {});
-              });
-            });
-          });
-        });
-      });
-    });
-    test('after nest', () {
-      expect(s.toString(), "l1 U l2 U l4 U l5 U l6 D l4 D l2 D ");
-    });
-  });
-}
-
-
-Function makeDelayedSetup(int index, StringBuffer s) => () {
-  return new Future.delayed(new Duration(milliseconds: 1), () {
-    s.write('l$index U ');
-  });
-};
-
-Function makeDelayedTeardown(int index, StringBuffer s) => () {
-  return new Future.delayed(new Duration(milliseconds: 1), () {
-    s.write('l$index D ');
-  });
-};
-
-Function makeImmediateSetup(int index, StringBuffer s) => () {
-  s.write('l$index U ');
-};
-
-Function makeImmediateTeardown(int index, StringBuffer s) => () {
-  s.write('l$index D ');
-};