This will allow to artificially trigger GCs on all allocations for testing purposes.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/144543005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18787 ce2b1a6d-e550-0410-aec6-3dcde31c8c00