This fixes a corner case where a code flushing candidate was evicted
from the candidate list without being revisited by the incremental
marker. An explicit write-barrier makes sure it gets revisited.

R=ulan@chromium.org
BUG=chromium:159140
TEST=cctest/test-heap/Regress159140

Review URL: https://codereview.chromium.org/11451038

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13153 ce2b1a6d-e550-0410-aec6-3dcde31c8c00