Skip a failing test that is leaving directories in /tmp.

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.
 
 package/invalid_uri_test: Fail, OK # Fails intentionally
 
 [ $runtime == vm ]
-io/test_runner_test: Fail # Fails because checked-in dart executable is not up to date.
-io/skipping_dart2js_compilations_test: Fail # Fails because checked-in dart executable is not up to date.
+# Fails because checked-in dart executable is not up to date.
+io/test_runner_test: Fail
+# Fails because checked-in dart executable is not up to date.
+# Skip this because it is leaving temp directories behind when it fails.
+io/skipping_dart2js_compilations_test: Skip
 
 [ $runtime == vm && ( $system == windows ) ]
 io/raw_socket_test: Pass, Fail # Issue 8901
 
 [ $runtime == vm ]
 package/package_isolate_test: Fail # http://dartbug.com/7520.
 io/raw_server_socket_cancel_test: Pass, Fail, Timeout # Issue 8675
 
 [ $runtime == vm && $checked ]
 # These tests have type errors on purpose.
@@ skipping 100 matching lines @@
 *: Skip
 
 [ $arch == simarm ]
 *: Skip
 
 [ $arch == mips ]
 *: Skip
 
 [ $arch == simmips ]
 *: Skip