As of https://chromium-review.googlesource.com/c/v8/v8/+/2452689 ,
ObjectCacheIndexMap uses IdentityMap which deals with GC gracefully.

Change-Id: I6d43ee2c1e330556b0ab7e4a6c313d5b37086343
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2742615Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73266}