Use the same IP address for both server and client in web_socket_pipe_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.
 
 # The testing infrastructure is using the dart:io Path and LineTransformer
@@ skipping 17 matching lines @@
 # These test have type errors on purpose and take very long to run in
 # checked mode with no benefit. Skip.
 io/file_fuzz_test: Skip
 io/directory_fuzz_test: Skip
 
 [ $runtime == vm && $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
-io/web_socket_pipe_test: Skip # Issue 12974
 
 # These tests pass on MacOS 10.8.2 but fails on the buildbot machines
 # that are running an earlier version of MacOS. The issue is that the
 # old version of MacOS does not expand the precomposed utf-8 it gets
 # from the VM before comparing it to the decomposed utf-8 used for the
 # file system.
 io/file_non_ascii_sync_test: Pass, Fail
 io/file_non_ascii_test: Pass, Fail
 io/directory_non_ascii_sync_test: Pass, Fail
 io/directory_non_ascii_test: Pass, Fail
 io/process_non_ascii_test: Pass, Fail
 
 [ $runtime == vm && $system == windows ]
-io/web_socket_pipe_test: Skip # Issue 12974
 io/http_server_early_client_close_test: Crash, Pass # Issue 12982
 
 [ $compiler == none && $runtime == drt ]
 typed_data_isolate_test: Skip # This test uses dart:io
 io/*: Skip # Don't run tests using dart:io in the browser
 package/*: Skip # Do not run those in Dartium.
 debugger/*: Skip # Do not run standalone debugger tests in browser.
 coverage_test: Skip
 http_launch_test: Skip
 vmservice/*: Skip # Do not run standalone vm service tests in browser.
@@ skipping 101 matching lines @@
 io/web_socket_test: Pass, Slow
 io/http_server_response_test: Pass, Slow
 out_of_memory_test: Skip # passes on Mac, crashes on Linux
 oom_error_stacktrace_test: Skip # Fails on Linux
 
 [ $arch == mips ]
 io/test_extension_test: Fail
 io/test_extension_fail_test: Fail
 io/dart_std_io_pipe_test: Fail
 io/file_read_special_device_test: Fail