With the flag enabled, that phase runs in the background as part
of OptimizeGraph.

Bug: v8:7790
Change-Id: I313578c113be1fb76dfc315522906178bee1027d
Reviewed-on: https://chromium-review.googlesource.com/c/1268156Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56624}