This reverts commit 566233ae.

Reason for revert: Breaks the build

Original change's description:
> Extend IsExtensible proxy trap fast path for Reflect.isExtensible
> 
> The fast path for IsExtensible proxy trap is already implemented, we just need to use this for ReflectIsExtensible.
> Now, ReflectIsExtensible is now a Torque builtin (previously CPP). Other cases will fall back to runtime.
> 
> Bug: v8:6664
> Change-Id: Ib1c3f78d1f1a44c6628d351fed3bcdc91ca08cb5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1645438
> Reviewed-by: Maya Lekova <mslekova@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Tamer Tas <tmrts@chromium.org>
> Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
> Cr-Commit-Position: refs/heads/master@{#62031}

TBR=jgruber@chromium.org,mslekova@chromium.org,tmrts@chromium.org,duongn@microsoft.com

Change-Id: I92f83d8c9cbdca1a33ddd0e875551deb62d7de89
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6664
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1648241Reviewed-by: Dan Elphick <delphick@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62033}