This reverts commit 3a46c81c.

Reason for revert: Breaking roll (or rather, oh no, cast_shell is broken, need to fix that before relanding): https://ci.chromium.org/ui/p/chromium/builders/try/cast_shell_linux/1053410/overview

Original change's description:
> [flags] Add a sanity check for unchanged jitless flags
>
> V8 flags in general should not change in a process after the
> first Isolate has been initialized. --jitless and related flags
> especially sensitive to this, so we introduce a dedicated check
> just for them.
>
> Bug: chromium:1262676, v8:9019, v8:12366
> Change-Id: I239726889d236a3785c1fdc076fa21d1b8983c92
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3260508
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#77759}

Bug: chromium:1262676, v8:9019, v8:12366
Change-Id: Ie47d183bfd68633c3d30a13a038219051c38eba0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3268734
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Owners-Override: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#77785}