.. by the runtime flag --enable-experimental-regexp-engine.

Introduced in https://chromium-review.googlesource.com/c/v8/v8/+/2461244

Tbr: neis@chromium.org
Bug: v8:10765
Change-Id: Ic32464ced7e5ddb4c31fe165eddb6b9d19260efc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2516920
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70963}