Mark pkg/watcher/test/directory_watcher/polling_test as flaky

dart/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 308 matching lines @@
 http/test/request_test: StaticWarning
 http/test/streamed_request_test: StaticWarning
 intl/test/date_time_format_file_even_test: StaticWarning
 intl/test/date_time_format_file_odd_test: StaticWarning
 intl/test/date_time_format_http_request_test: StaticWarning
 intl/test/date_time_format_local_even_test: StaticWarning
 intl/test/date_time_format_local_odd_test: StaticWarning
 unittest/test/matchers_test: StaticWarning, OK # testing error creating abstract class
 unittest/test/mock_test: StaticWarning, OK # testing unimplemented members
 
+[ $runtime == vm ]
+watcher/test/directory_watcher/polling_test: Pass, Fail # Issue 15034
+
 [ $runtime == vm && ($system == windows || $system == macos) ]
 watcher/test/*/linux_test: Skip
 
 [ $runtime == vm && ($system == windows || $system == linux) ]
 watcher/test/*/mac_os_test: Skip
 
 [ $runtime == vm && $system == linux ]
 watcher/test/*/linux_test: Pass, Slow # Issue 14606
 
 [ $runtime == vm && $system == macos ]
 watcher/test/no_subscribers/mac_os_test: Fail # Issue 14793 (see test file for details)
 watcher/test/directory_watcher/mac_os_test: Pass, Fail # Issue 15042