Apply workaround for bug 13921 to new test in pkg/unittest.

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
@@ skipping 355 matching lines @@
 # Timeout. These are not unit tests. They do not run efficiently on our
 # simulator.
 *: Skip
 
 # Skip serialization test that explicitly has no library declaration in the
 # test on Dartium, which requires all tests to have a library.
 [ $compiler == none && ( $runtime == dartium || $runtime == drt || $runtime == ContentShellOnAndroid) ]
 serialization/test/no_library_test: Skip # Expected Failure
 serialization/test/serialization_test: Fail # 13921
 unittest/test/async_exception_test: RuntimeError # 13921
+unittest/test/async_exception_with_future_test: RuntimeError # 13921
 unittest/test/async_setup_teardown_test: RuntimeError # 13921
 unittest/test/completion_test: RuntimeError # 13921
 unittest/test/correct_callback_test: RuntimeError # 13921
 unittest/test/exception_test: RuntimeError # 13921
 unittest/test/excess_callback_test: RuntimeError # 13921
 unittest/test/expect_async_args_test: RuntimeError # 13921
 unittest/test/expect_async_test: RuntimeError # 13921
 unittest/test/group_name_test: RuntimeError # 13921
 unittest/test/invalid_ops_test: RuntimeError # 13921
 unittest/test/late_exception_test: RuntimeError # 13921
@@ skipping 76 matching lines @@
 oauth2/test/authorization_code_grant_test: Fail
 oauth2/test/client_test: Fail
 oauth2/test/credentials_test: Fail
 oauth2/test/handle_access_token_response_test: Fail
 
 [ $runtime == drt ]
 http/test/html/client_test: Skip # Issue 18566
 
 [ $mode == debug ]
 analysis_server/test/integration/analysis_domain_int_test: Slow, Pass