Allow use of phase-local zone in GenericGraphVisit.

R=titzer@chromium.org, bmeurer@chromium.org

Review URL: https://codereview.chromium.org/467103003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23103 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Temporary workaround for scheduler running OOM.

R=titzer@chromium.org
TEST=benchmarks/octane/zlib

Review URL: https://codereview.chromium.org/468863002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23104 ce2b1a6d-e550-0410-aec6-3dcde31c8c00