This refactors Map operations to update the instance descriptors and
the number of own descriptors via the SetInstanceDescriptors bottleneck.
This will allow us to add a special marking barrier for these updates.

Bug: v8:8486
Change-Id: Ie9c746d4bcdd6166d38402622734693fa59faf21
Reviewed-on: https://chromium-review.googlesource.com/c/1354883Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57934}