should_skip = name => {
        return this.is_excluded_by_options(name, options);
    }
Internal helper called by add_idls() and add_untested_idls().

parsed_idls is an array of objects that come from WebIDLParser.js's
"definitions" production.  The add_untested_idls() entry point
additionally sets an .untested property on each object (and its
.members) so that they'll be skipped by test() -- they'll only be
used for base interfaces of tested interfaces, return types, etc.

options is a dictionary that can have an only or except member which are
arrays. If only is given then only members, partials and interface
targets listed will be added, and if except is given only those that
aren't listed will be added. Only one of only and except can be used.