Now that we are using PersistentHandles, we don't need it anymore.

Bug: v8:7790
Change-Id: Id0b9d555191c00fb08dc2bb9099746076c5ad1b7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2332161
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69278}