This fixes a memory leak.

Bug: v8:9191, v8:7790
Change-Id: I0df49cd3a6791600638a67b4b7ad9687562e500b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1588426
Commit-Queue: Georg Neis <neis@chromium.org>
Auto-Submit: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61166}