Skip tests for `unittest` in dartium.

pkg/pkg.status

 # Copyright (c) 2012, 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.
 
 # Don't run any test-like files that show up in packages directories. It
 # shouldn't be necessary to run "pub install" in these packages, but if you do
 # it shouldn't break the tests.
 */packages/*/*: Skip
 */*/packages/*/*: Skip
 */*/*/packages/*/*: Skip
 */*/*/*/packages/*/*: Skip
 */*/*/*/*/packages/*/*: Skip
 
 [ $compiler == none && ($runtime == drt || $runtime == dartium || $runtime == ContentShellOnAndroid) ]
 third_party/angular_tests/browser_test/*: Skip # github perf_api.dart issue 5
 third_party/angular_tests/browser_test/core_dom/shadow_root_options: Fail # Issue 19329
 mutation_observer: Skip # Issue 21149
+unittest/*: Skip # Issue 21949
 
 [ $runtime == vm && $mode == debug]
 analysis_server/test/analysis_server_test: Skip  # Times out
 analysis_server/test/completion_test: Skip  # Times out
 analysis_server/test/domain_context_test: Skip  # Times out
 analysis_server/test/domain_server_test: Skip  # Times out
 analysis_server/test/integration/analysis/reanalyze_concurrent_test: Skip # Times out
 analysis_server/test/integration/analysis/update_content_test: Skip # Times out
 analysis_server/tool/spec/check_all_test: Skip # Times out
 analyzer/test/generated/element_test: Skip  # Times out
@@ skipping 146 matching lines @@
 
 [ $unchecked ]
 third_party/angular_tests/browser_test/angular: Skip # Requires checked mode.
 third_party/angular_tests/browser_test/core/scope: Skip # Requires checked mode.
 third_party/angular_tests/browser_test/core/zone: Skip # Requires checked mode.
 third_party/angular_tests/browser_test/directive/ng_repeat: Skip # Issue 17152
 third_party/angular_tests/browser_test/change_detection/dirty_checking_change_detector: Skip # Issue 17152
 
 [ $use_repository_packages ]
 analyzer/test/*: PubGetError