This reverts commit dc1cc223.

Revert "[regexp] Implement the match indices proposal"

This reverts commit 9460101c.

Reason for revert: Causes confusion on Blink side, as it introduces
an object with >=2 internal fields that is not a wrapper (see bug).

Bug: chromium:996681
Change-Id: I5c167e9e15bfbec2aa6b843e3063ead5d52fb26c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768897
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63376}