Revert "Mark mjsunit/string-case as flaky."

This reverts r19760 since the issue has been fixed in r19755.

R=dslomov@google.com, dslomov@chromium.org
BUG=v8:3208
LOG=N

Review URL: https://codereview.chromium.org/194823002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19793 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/mjsunit/mjsunit.status

@@ -134,10 +134,6 @@
   '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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