Skip mjsunit/migrations test in debug mode to avoid timeout failures.

TBR=yangguo@chromium.org

Review URL: https://codereview.chromium.org/364663002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22133 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/mjsunit/mjsunit.status

@@ -87,7 +87,7 @@
   ##############################################################################
   # Skip long running tests that time out in debug mode.
   'generated-transition-stub': [PASS, ['mode == debug', SKIP]],
-  'migrations': [PASS, ['mode == debug', SLOW]],
+  'migrations': [PASS, ['mode == debug', SKIP]],
 
   ##############################################################################
   # This test sets the umask on a per-process basis and hence cannot be