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

pkg/unittest/lib/html_individual_config.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.
-
-/// A unit test library for running groups of tests in a browser, instead of the
-/// entire test file. This is especially used for large tests files that have
-/// many subtests, so we can mark groups as failing at a finer granularity than
-/// the entire test file.
-///
-/// To use, import this file, and call [useHtmlIndividualConfiguration] at the
-/// start of your set sequence. Important constraint: your group descriptions
-/// MUST NOT contain spaces.
-library unittest.html_individual_config;
-
-import 'dart:html';
-import 'unittest.dart' as unittest;
-import 'html_config.dart' as htmlconfig;
-
-class HtmlIndividualConfiguration extends htmlconfig.HtmlConfiguration {
-  HtmlIndividualConfiguration(bool isLayoutTest): super(isLayoutTest);
-
-  void onStart() {
-    var search = window.location.search;
-    if (search != '') {
-      var groups = search.substring(1).split('&')
-          .where((p) => p.startsWith('group='))
-          .toList();
-
-      if (!groups.isEmpty) {
-        if (groups.length > 1) {
-          throw new ArgumentError('More than one "group" parameter provided.');
-        }
-
-        var testGroupName = groups.single.split('=')[1];
-        var startsWith = "$testGroupName${unittest.groupSep}";
-        unittest.filterTests((unittest.TestCase tc) =>
-            tc.description.startsWith(startsWith));
-      }
-    }
-    super.onStart();
-  }
-}
-
-void useHtmlIndividualConfiguration([bool isLayoutTest = false]) {
-  unittest.unittestConfiguration = isLayoutTest ? _singletonLayout : _singletonNotLayout;
-}
-
-final _singletonLayout = new HtmlIndividualConfiguration(true);
-final _singletonNotLayout = new HtmlIndividualConfiguration(false);