Fix test expectations for io/file_lock_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.
 
 io/raw_socket_test: Pass, RuntimeError # Issue 28288
@@ skipping 224 matching lines @@
 package/package_isolate_test: Crash # Issue 28645
 package/scenarios/empty_packages_file/empty_packages_file_noimports_test: Crash # Issue 28645
 package/scenarios/empty_packages_file/empty_packages_file_option_test: Crash, Pass # Issue 28645
 package/scenarios/packages_file_strange_formatting/empty_lines_test: Crash # Issue 28645
 package/scenarios/packages_file_strange_formatting/empty_package_dir_test: Crash # Issue 28645
 package/scenarios/packages_file_strange_formatting/mixed_line_ends_test: Crash # Issue 28645
 package/scenarios/packages_option_only/packages_option_only_noimports_test: Crash # Issue 28645
 package/scenarios/packages_option_only/packages_option_only_test: Crash, CompileTimeError # Issue 28645
 
 [ $compiler == dartk && $mode == debug ]
-io/file_lock_test: Slow
+io/file_lock_test: Slow, Pass
 
 [ ($runtime == vm || $runtime == dart_precompiled) && $mode == debug && $builder_tag == asan ]
 io/file_lock_test: Skip  # Timeout.
 io/test_runner_test: Skip  # Timeout.
 io/http_client_stays_alive_test: Skip  # Timeout.
 
 [ $runtime == vm || $runtime == dart_precompiled ]
 # Failures in secure networking while NSS is replaced with BoringSSL
 io/https_client_certificate_test: RuntimeError # Issue 24070
 io/secure_socket_renegotiate_test: RuntimeError
@@ skipping 201 matching lines @@
 io/uri_platform_test: DartkCrash
 map_insert_remove_oom_test: Crash
 package/package1_test: CompileTimeError
 package/package_test: CompileTimeError
 package/scenarios/invalid/invalid_package_name_test: DartkCrash
 package/scenarios/invalid/invalid_utf8_test: DartkCrash
 package/scenarios/invalid/non_existent_packages_file_test: DartkCrash
 package/scenarios/invalid/same_package_twice_test: DartkCrash
 package/scenarios/packages_dir_only/packages_dir_only_test: CompileTimeError
 verbose_gc_to_bmu_test: RuntimeError