Close 'accepted' sockets when listening socket is closed. Fixes raw_server_socket_cancel_test.

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.
 
 package/invalid_uri_test: Fail, OK # Fails intentionally
 
 [ $runtime == vm ]
 io/web_socket_test: Pass, Crash # Issue 11502
 
 [ $runtime == vm ]
 package/package_isolate_test: Fail # http://dartbug.com/7520.
-# The test is flaky, and is timing out, causing buildbot cycle times to rise.
-io/raw_server_socket_cancel_test: Skip # Issue 8675
 
 [ $runtime == vm && $checked ]
 # These tests have type errors on purpose.
 io/process_invalid_arguments_test: Fail, OK
 io/directory_invalid_arguments_test: Fail, OK
 io/file_invalid_arguments_test: Fail, OK
 io/socket_invalid_arguments_test: Fail, OK
 io/stdout_bad_argument_test: Fail, OK
 # These test have type errors on purpose and take very long to run in
 # checked mode with no benefit. Skip.
@@ skipping 118 matching lines @@
 
 [ $arch == simarm ]
 out_of_memory_test: Skip # passes on Mac, crashes on Linux
 
 [ $arch == mips ]
 *: Skip
 
 [ $arch == simmips ]
 io/file_fuzz_test: Pass, Timeout
 out_of_memory_test: Skip # passes on Mac, crashes on Linux