[Sheriff] Mark flaky test.

test/mjsunit/mjsunit.status

 # Copyright 2012 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 16 matching lines @@
 
 [
 [ALWAYS, {
   # All tests in the bug directory are expected to fail.
   'bugs/*': [FAIL],
 
   # TODO(mvstanton) Re-enable when the performance is bearable again.
   'regress/regress-2185-2': [SKIP],
 
   ##############################################################################
+  # Flaky tests.
+  # BUG(v8:2921): Flaky on ia32 nosnap, arm and nacl.
+  'debug-step-4-in-frame': [PASS, [('system == linux and arch == ia32 or '
+                                    'arch == arm or arch == nacl_ia32 or '
+                                    'arch == nacl_x64'), FLAKY]],
+
+  ##############################################################################
   # Fails.
   'regress/regress-1119': [FAIL],
 
   # Issue 1719: Slow to collect arrays over several contexts.
   'regress/regress-524': [SKIP],
   # When that bug is fixed, revert the expectation to:
   # Skip long running test in debug and allow it to timeout in release mode.
   # regress/regress-524: [PASS, TIMEOUT, ['mode == debug', SKIP]],
 
   # This test non-deterministically runs out of memory on Windows ia32.
@@ skipping 215 matching lines @@
   'never-optimize': [SKIP],
   'regress/regress-2185-2': [SKIP],
   'harmony/object-observe': [SKIP],
   'readonly': [SKIP],
   'array-feedback': [SKIP],
 
   # Deopt every n garbage collections collides with deopt every n times.
   'regress/regress-2653': [SKIP],
 }],  # 'deopt_fuzzer == True'
 ]