darobin/webidl2.js — pull request #20 by othree (2014-12-05 06:45:19+00:00)
Title: Support ID list in extended attributes

WebIDL 2nd edition support identifier list at right hand side of extended attribute.
WebIDL 2 is not a W3C recommendation.
But many new spec is using this, ex: html5, fetch

ref: https://heycam.github.io/webidl/#dfn-extended-attribute