RFC: https://wiki.php.net/rfc/trailing_comma_in_closure_use_list
Discussion: https://externals.io/message/110715
The release manager has agreed to allow merging of RFCs that have near-unanimous
votes. If an RFC ends up not achieving the required 2/3 majority at the time the
announced voting period closes, this implementation commit will be reverted
in time for the feature freeze.
Closes GH-5793
