Previously, when the Load IC saw a deprecated map, it would migrate to
the new map but not update the feedback vector. This would lead to a
deopt the next time the same object was seen.

With this CL, the feedback vector will be updated to the target of the
deprecated map. In order to do this, we need to mark the IC for
recomputation. Without that call, the map and handler would look the
same to IC::UpdatePolymorphicIC amd would decline to update, causing
the IC to go megamorphic instead.

Bug: v8:10816
Change-Id: I0dcf97fb278bc0b167df6ce24d5db179f599f535
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3032983Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Kevin Babbitt <kbabbitt@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#76042}