This reverts commit b8f91666.

Reason for revert: Fails gc-stress (https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20gc%20stress/28341).

Original change's description:
> [flags] warn about contradictory flags
> 
> Design Doc: https://docs.google.com/document/d/1lkvu8crkK7Ei39qjkPCFijpNyxWXsOktG9GB-7K34jM/
> 
> Bug: v8:10577
> Change-Id: Ib9cfdffa401c48c895bf31caed5ee03545beddab
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2154792
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Reviewed-by: Tamer Tas <tmrts@chromium.org>
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#68168}

TBR=machenbach@chromium.org,neis@chromium.org,clemensb@chromium.org,tebbi@chromium.org,tmrts@chromium.org

Change-Id: Ia1e3373fbb4c369594ceb98eb560e3ccf2cb8780
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10577
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2230523Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68169}