Mark mjsunit/string-case as flaky.

BUG=v8:3208
LOG=N
R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/192573004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19760 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/mjsunit/mjsunit.status

@@ -134,6 +134,10 @@
   'osr-elements-kind': [SKIP],
   'regress/regress-165637': [SKIP],
   'regress/regress-2249': [SKIP],
+
+  # Tests failing GC stress - possible bugs.
+  # BUG(v8:3208)
+  'string-case': [FLAKY, PASS],
 }],  # 'gc_stress == True'
 
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