Skip gc-stress for test relying on stable feedback (and hence stable gc timing).

BUG=
R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/441873005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22852 ce2b1a6d-e550-0410-aec6-3dcde31c8c00