InvalidatedSlotsCleanup::Free assumed that the size of invalidated
objects was updated after sweeping a page and before allowing
allocations again. This is now not the case anymore, so remove
those CHECKs.

Bug: chromium:997901
Change-Id: Ic9af7136bb336464b8cc023c7c1022a233f4e887
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771786
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63412}