This makes the DCHECK consistent with the map updater.
See https://cs.chromium.org/chromium/src/v8/src/map-updater.cc?l=330&rcl=5671f8b940b0fcdb550e318e449ded0f866e935a

Bug: chromium:949435
Change-Id: Id4fef60cdca094e638a1db38878953ecb2422c4f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1552797Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60640}