The former implementation lacked symbols on the iterator objects
without prototype. This is now fixed.
The special handling for overriding `Symbol.iterator` was removed as
it's very difficult to deal with this properly. Manipulating the
symbols is just not supported.
PR-URL: https://github.com/nodejs/node/pull/22437
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>