Using Punycode.js as a named module in RequireJS

 Punycode.js has conditional code to declare itself as a RequireJS module (when RequireJS is previously loaded).

If other scripts declare RequireJS named modules, Punycode.js causes this error:

Error: Mismatched anonymous define() module: function () ...

https://groups.google.com/forum/#!searchin/joomla-dev-cms/punycode/joomla-dev-cms/ZdCfpSvXLsI/l7TssShte6MJ

To avoid this conflict, all RequireJS modules in Joomla core must be named modules.

In this case, the PR just defines Punycode name as 'punycode'.
define('punycode', function() ...

The change does not affect the regular form validation. (http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33105&start=0).

It only defines the module name if RequireJS is loaded.

Joomlacode: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33277&start=0