Skip test that sometimes hangs on Mac.

tests/standalone/standalone.status

 # 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.
 
 # WARNING:
 # Tests using the multitest feature where failure is expected should *also* be
 # listed in tests/lib/analyzer/analyze_tests.status without the "standalone"
 # prefix.
 
 packages_file_test: Skip # Issue 26715
@@ skipping 32 matching lines @@
 
 [ ($runtime == vm || $runtime == dart_precompiled) && $system == macos ]
 # This test fails with "Too many open files" on the Mac OS buildbot.
 # This is expected as MacOS by default runs with a very low number
 # of allowed open files ('ulimit -n' says something like 256).
 io/socket_many_connections_test: Skip
 # Re-enable once the bots have been updated. Issue #26057
 io/secure_server_client_certificate_test: Skip
 io/socket_test: Pass, Timeout # Issue 27453
 
+# This test sometimes hangs on Mac.
+io/raw_server_socket_cancel_test: Skip # Issue 28182
+
 [ $runtime == vm && $system == linux ]
 # These tests have started timing out and issue 25649 has been filed to
 # investigate, skipping these tests temporarily to get the bots to be
 # green again.
 io/http_proxy_test: Skip
 io/secure_builtin_roots_test: Skip
 
 
 [ $compiler == none && ($runtime == drt || $runtime == dartium) ]
 typed_array_test: RuntimeError, OK  # Uses Isolate.spawn
@@ skipping 295 matching lines @@
 
 [ $builder_tag == no_ipv6 ]
 io/http_bind_test: SkipByDesign
 io/raw_datagram_socket_test: SkipByDesign
 io/socket_source_address_test: SkipByDesign
 io/socket_bind_test: SkipByDesign
 io/http_proxy_advanced_test: SkipByDesign
 io/http_ipv6_test: SkipByDesign
 io/socket_ipv6_test: SkipByDesign
 io/socket_info_ipv6_test: SkipByDesign