Since unboxed doubles are removed already, MigrateFastToSlow doesn't
need to invalidate old-to-old-slots anymore.

Bug: chromium:1188483
Change-Id: I0875fc0c8bcf8086f22678ffbbef000fd94ea7ea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2764745Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73456}