Fix bug in web socket close handling

tests/standalone/standalone.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.
 
 timeout_test: Skip  # Timeout test for testing the test runner.
 fail_test: Fail, OK # Fails intentionally
 out_of_memory_test: Skip # Issue 2345
 
 package/invalid_uri_test: Fail, OK # Fails intentionally
 
@@ skipping 11 matching lines @@
 [ $runtime == vm && $system == macos]
 # This test fails with "Too many open files" on the Mac OS buildbot.
 io/socket_many_connections_test: Skip
 io/test_extension_test: Skip  # Extensions not implemented on MacOS
 io/http_server_handler_test: Skip # Issue 2637
 
 [ $runtime == vm && $system == windows]
 io/test_extension_test: Skip  # Extensions not implemented on Windows
 io/http_shutdown_test: Skip  # Currently times out on windows
 io/file_system_links_test: Skip  # No links on Windows.
-io/web_socket_test: Pass, Fail  # Issue 2867 (flaky)
 
 [ $compiler == none && $runtime == drt ]
 io/*: Skip # Don't run tests using dart:io in the browser
 crypto/*: Skip # Don't run tests using dart:io in the browser
 package/*: Skip # Do not run those in Dartium.
 
 [ $compiler == dartc]
 *: Skip
 
 [ $compiler == frog || ($compiler == dart2js && $runtime == drt) ]
@@ skipping 19 matching lines @@
 assert_test: Fail # Assert not implemented
 byte_array_test: Fail, OK # ByteArray
 deoptimization_test: Fail, OK # Requires bigint.
 out_of_memory_test: Fail, OK # d8 handles much larger arrays than Dart VM.
 io/http_parser_test: Fail, OK # ByteArray
 io/options_test: Fail, OK # Cannot pass options to d8.
 
 [ $compiler == dart2js && $runtime == none ]
 fail_test: Skip # fails only at runtime, overrides default expectation from standalone.status
 io/options_test: Fail