JSRegex does not have custom body descriptor and uses JSObject body
descriptor, so it should just use JSObject visitor id.

Bug: chromium:825828
Change-Id: Iae22315da7ab83bb4ac919586c883120621761c8
Reviewed-on: https://chromium-review.googlesource.com/980752Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52228}