This reverts commit f7f72b7b.

Reason for revert: Flaky timeouts of slow-path tests -- specifically, mjsunit/regress/wasm/regress-9017, which appears to have regressed from ~2 min to ~3-4 min 

https://logs.chromium.org/logs/v8/buildbucket/cr-buildbucket.appspot.com/8878016799136124416/+/steps/Check_-_slow_path__flakes_/0/logs/regress-9017/0

Original change's description:
> [wasm-simd] Prototype f64x2 rounding instructions
> 
> Implements f64x2 ceil, floor, trunc, nearestint, for interpreter and
> x64.
> 
> Bug: v8:10553
> Change-Id: I12a260a3b1d728368e5525d317d30fc9581cae04
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2213082
> Commit-Queue: Zhi An Ng <zhin@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#68241}

TBR=gdeepti@chromium.org,tebbi@chromium.org,zhin@chromium.org

Change-Id: I9915dd375c7f0e08b5414189efb29ed1c90cb96d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10553
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2237131Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68248}