nl_tokens: https : // html . spec . whatwg . org / multipage / links . html#link - type - stylesheet
pl_tokens: function maybeFetchAndProcess ( <mask> ) { if ( ! isExternalResourceLink ( el ) ) { return ; } // Browsing-context connected if ( ! el . isConnected || ! el . _ownerDocument . _defaultView ) { return ; } fetchAndProcess ( el ) ; }