This reverts commit c1bf25bb.

Reason for revert: We got many regressions:

https://chromeperf.appspot.com/group_report?rev=58157

Original change's description:
> Enable 31bit Smis everywhere
> 
> This is a experiment to see how performance is impacted. If we tank
> too much, we can revert this change.
> 
> Change-Id: I01be33f5dd78aee6a5beecdc62adbaa6c3850eb1
> Bug: v8:8344
> Reviewed-on: https://chromium-review.googlesource.com/c/1355279
> Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#58157}

TBR=jarin@chromium.org,sigurds@chromium.org,ishell@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:8344
Change-Id: I407cb99743a08452edcecfc2e945ef98509e8d32
Reviewed-on: https://chromium-review.googlesource.com/c/1375911Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58227}