This reverts commit 50a80c93.

Reason for revert: We want to understand if this change is
necessary to avoid renderer hangs.

Original change's description:
> [turbofan] Make hints equality cheaper using hashing
> 
> Put the nesting limit of the serializer back to 25.
> 
> Bug: chromium:1034768
> Change-Id: I7ea827d27241ea930bae40142069bab1962e4133
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1981156
> Commit-Queue: Maya Lekova <mslekova@chromium.org>
> Reviewed-by: Michael Stanton <mvstanton@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65630}

TBR=mvstanton@chromium.org,mslekova@chromium.org

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

Bug: chromium:1034768
Change-Id: I7aaf71e665e35999ea9c1b8d2680678add17bf96
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2010115Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65881}