Even if the old-to-old remembered set contains a slot it should be
considered cleared if it was added into the invalidated slot set.

Change-Id: I30db5a77b14e729ab45b6de82af8795d85263518
Reviewed-on: https://chromium-review.googlesource.com/1224095
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55856}