As per TODO, this is its rightful place, which gets the module-compiler
out of the business of doing finalization.

R=mstarzinger@chromium.org,clemensh@chromium.org

Bug: v8:7316
Change-Id: Ie419a1e348f14f2613f62fed7083e19365cd9347
Reviewed-on: https://chromium-review.googlesource.com/880950Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50805}