* improve util.inspect performance
This is a huge performance improvement in case of sparse arrays
when using util.inspect as the hole will simple be skipped.
* use faster visibleKeys property lookup
* add inspect-array benchmark
PR-URL: https://github.com/nodejs/node/pull/14492
Fixes: https://github.com/nodejs/node/issues/14487
Reviewed-By: Alexey Orlenko <eaglexrlnk@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
