The Isolate* parameter in the deserializer SanityCheck is unused, and is
blocking the use of the deserializer off-thread.

Bug: chromium:1075999
Change-Id: I0f2acae3c1aff62aafeb2680a2eecb44b1608803
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2184290
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67594}