Some tests involving AllocationSites are failing in GcStress test mode.

Some tests involving AllocationSites are failing in GcStress test mode.
The reason is that an AllocationMemento associated with an array only
lives for one gc (it is unrooted). So an excess of garbage collections
in these tests cause the Memento to be lost, and expected behavior
can't be guaranteed.

BUG=
R=hpayer@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=15714

[mvstanton, 2013-07-17 08:27:55]

Hi Hannes, here is the fix we discussed. The wording around "GcStress" I got
from another test which turns it off: mjsunit/regress-165637.js

Thanks,
--Michael

[Hannes Payer (out of office), 2013-07-17 08:29:53]

lgtm

[mvstanton, 2013-07-17 11:42:37]

Committed patchset #1 manually as r15714 (presubmit successful).