This flag's name is slightly incorrect as it is possible to have more
maps than this in the feecback vector.

This flag doesn't account for deprecated maps in the feedback
vector. To make this explicit, we change the flag to indicate that
this only counts valid maps.

Bug: v8:10582
Change-Id: Ib0cc425a03d590bb21184fc6b104d0ebee1d5b03
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2319992Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69075}