Issue 4350 - Update punycode.js to 2.0.0

lib/punycode.js

 /*
- * Copyright Mathias Bynens <https://mathiasbynens.be/>

[Sebastian Noack, 2016/08/23 16:27:06]

The MIT license header seems to require a copyright year. Also I guess we'd have
to add ourselves as copyright holder since we modify some parts of the code.

[kzar, 2016/08/23 16:51:13]

Done. (I put 2011-2016 after looking at his repository's commit history
https://github.com/bestiejs/punycode.js/commits/master?page=4 )

+ * Copyright (C) 2011-2016 Mathias Bynens <https://mathiasbynens.be/>
+ * Copyright (C) 2016 Eyeo GmbH (Minor modifications for compatibility.)
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sublicense, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice shall be
@@ skipping 416 matching lines @@
         return mapDomain(input, function(string) {
                 return regexNonASCII.test(string)
                         ? 'xn--' + encode(string)
                         : string;
         });
 };
 
 /*--------------------------------------------------------------------------*/
 
 /** Define the public API */
-const punycode = exports = {

[Sebastian Noack, 2016/08/23 16:27:06]

It seems the punycode object isn't used anywhere inside this module. So just
assigning to exports, without creating the punycode variable, will do.

[kzar, 2016/08/23 16:51:13]

Done.

+exports = {
         /**
          * A string representing the current Punycode.js version number.
          * @memberOf punycode
          * @type String
          */
         'version': '2.0.0',
         /**
          * An object of methods to convert from JavaScript's internal character
          * representation (UCS-2) to Unicode code points, and back.
          * @see <https://mathiasbynens.be/notes/javascript-encoding>
          * @memberOf punycode
          * @type Object
          */
         'ucs2': {
                 'decode': ucs2decode,
                 'encode': ucs2encode
         },
         'decode': decode,
         'encode': encode,
         'toASCII': toASCII,
         'toUnicode': toUnicode
 };