See https://github.com/tc39/proposal-regexp-named-groups/pull/40.

The spec is being changed to always create a 'groups' property on
regexp result objects. Its value is undefined if no named captures
exist, and the object containing named captures otherwise.

Bug: v8:7192, v8:5437
Change-Id: I1fb00ffc186c7effd84b5692dcbed420581855c3
Reviewed-on: https://chromium-review.googlesource.com/829137Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50154}