Remove unittest and matcher from the repo.

pkg/unittest/test/expect_async_args_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.expect_async_args_test;
-
-import 'package:unittest/unittest.dart';
-
-import 'package:metatest/metatest.dart';
-
-void main() => initTests(_test);
-
-void _test(message) {
-  initMetatest(message);
-
-  expectTestResults('expect async args', () {
-    var count = 0;
-    List<int> _getArgs([a = 0, b = 0, c = 0, d = 0, e = 0, f = 0]) {
-      count++;
-      return [a, b, c, d, e, f];
-    }
-
-    test('expect async args', () {
-      expect(expectAsync(_getArgs)(), [0, 0, 0, 0, 0, 0]);
-      expect(expectAsync(_getArgs)(5), [5, 0, 0, 0, 0, 0]);
-      expect(expectAsync(_getArgs)(1, 2, 3, 4, 5, 6), [1, 2, 3, 4, 5, 6]);
-    });
-
-    test('invoked with too many args', () {
-      expectAsync(_getArgs)(1, 2, 3, 4, 5, 6, 7);
-    });
-
-    test('created with too many args', () {
-      expectAsync((a1, a2, a3, a4, a5, a6, a7) {
-        count++;
-      })();
-    });
-
-    test('verify count', () {
-      expect(count, 3);
-    });
-  }, [{
-    'description': 'expect async args',
-    'result': 'pass',
-  }, {
-    'description': 'invoked with too many args',
-    'result': 'error',
-  }, {
-    'description': 'created with too many args',
-    'result': 'error',
-  }, {
-    'description': 'verify count',
-    'result': 'pass',
-  }]);
-}