We must perform "smi-checks" before loading an object's map
whenever the object might be an i31ref.

Bug: v8:7748
Change-Id: I2d9839ddcb0c2e8c35b9bea38afe50d55dd084cb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2299370Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68893}