This reverts commit ff22ae80.

Reason for revert: new test fails on UBSAN
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20UBSan/10831

Original change's description:
> [turbofan][csa] optimize Smi untagging better
> 
> - Introduce new operator variants for signed right-shifts with the
>   additional information that they always shift out zeros.
> - Use these new operators for Smi untagging.
> - Merge left-shifts with a preceding Smi-untagging shift.
> - Optimize comparisons of Smi-untagging shifts to operate on the
>   unshifted word.
> - Optimize 64bit comparisons of values expanded from 32bit to use
>   a 32bit comparison instead.
> - Change CodeStubAssembler::UntagSmi to first sign-extend and then
>   right-shift to enable better address computations for Smi indices.
> 
> Bug: v8:9962
> Change-Id: If91300f365e8f01457aebf0bd43bdf88b305c460
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2135734
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#67378}

TBR=neis@chromium.org,tebbi@chromium.org

Change-Id: I2617d7a44e5ae33fd79322d37c8b722c00162d22
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9962
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2165873Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67380}