Fix d8-os unit test to be skipped for isolates.

test/mjsunit/mjsunit.status

 # Copyright 2011 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 48 matching lines @@
 unicode-case-overoptimization: PASS, TIMEOUT if ($arch == arm || $arch == mips)
 
 # Skip long running test in debug and allow it to timeout in release mode.
 regress/regress-524: (PASS || TIMEOUT), SKIP if $mode == debug
 
 # Stack manipulations in LiveEdit are buggy - see bug 915
 debug-liveedit-check-stack: SKIP
 debug-liveedit-patch-positions-replace: SKIP
 
 ##############################################################################
+[ $isolates ]
+
+# This test sets the umask on a per-process basis and hence cannot be
+# used in multi-threaded runs.
+d8-os: SKIP
+
+##############################################################################
 [ $arch == arm ]
 
 # Slow tests which times out in debug mode.
 try: PASS, SKIP if $mode == debug
 debug-scripts-request: PASS, SKIP if $mode == debug
 array-constructor: PASS, SKIP if $mode == debug
 
 # Flaky test that can hit compilation-time stack overflow in debug mode.
 unicode-test: PASS, (PASS || FAIL) if $mode == debug
 
@@ skipping 79 matching lines @@
 regress/regress-490: SKIP
 regress/regress-634: SKIP
 regress/regress-create-exception: SKIP
 regress/regress-3218915: SKIP
 regress/regress-3247124: SKIP
 
 # Requires bigger stack size in the Genesis and if stack size is increased,
 # the test requires too much time to run.  However, the problem test covers
 # should be platform-independent.
 regress/regress-1132: SKIP