Revert "Reland "Enable 31bit Smis everywhere""

This reverts commit b43e9d5e.

Reason for revert: Speculative revert, possibly breaking layout tests - https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8-Blink%20Linux%2064/29678

Original change's description:
> Reland "Enable 31bit Smis everywhere"
> 
> This is a reland of c1bf25bb
> 
> Node bot will turn green after github.com/v8/node/pull/89/
> has landed.
> 
> 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}
> 
> Bug: v8:8344
> Change-Id: I85a6e5c479f1090f50df3df042571227279a0692
> Reviewed-on: https://chromium-review.googlesource.com/c/1448314
> Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#59251}

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

Change-Id: Ie388de7e1cc28fcf8bc576f564f3b463002bf1b4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:8344
Reviewed-on: https://chromium-review.googlesource.com/c/1449533Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59272}

BUILD.gn

@@ -96,7 +96,7 @@ declare_args() {
 
   # Enable pointer compression (sets -dV8_COMPRESS_POINTERS).
   v8_enable_pointer_compression = false
-  v8_enable_31bit_smis_on_64bit_arch = true
+  v8_enable_31bit_smis_on_64bit_arch = false
 
   # Sets -dOBJECT_PRINT.
   v8_enable_object_print = ""