This fixes jumbo builds with enabled v8_postmortem_support.

Bug: v8:8838
Change-Id: Idf2efc3b94104ca1921b6de121df1c0aa7f3452c
Reviewed-on: https://chromium-review.googlesource.com/c/1470102
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59549}