... if FLAG_concurrent_compiler_frontend is enabled.

Bug: v8:7790
Change-Id: I448560b21d54c8907e8cbf68bdaf8bbdf2b034df
Reviewed-on: https://chromium-review.googlesource.com/1241959Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56205}