This reverts commit d04b5e47.

Reason for revert: closed the tree with a simd related test failure:
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64/37487?

Original change's description:
> [wasm-simd][liftoff][ia32][x64] Implement bitmask
> 
> Implements i8x16 i16x8 i32x4 bitmask.
> 
> This was merged into the proposal in
> https://github.com/WebAssembly/simd/pull/201/.
> 
> Bug: v8:9909,v8:10308
> Change-Id: I882f0c2697213cdf593e745112e0897cee252009
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2222607
> Commit-Queue: Zhi An Ng <zhin@chromium.org>
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#68090}

TBR=clemensb@chromium.org,zhin@chromium.org

Change-Id: I2e090f92d84b8f7d8bbf0725a4f64efaa18f3c65
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9909, v8:10308
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2223829Reviewed-by: Francis McCabe <fgm@chromium.org>
Commit-Queue: Francis McCabe <fgm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68091}