Build: Lint the minified jQuery file as well - a Gruntfile fix
Build: Lint the minified jQuery file as well - a Gruntfile fix

While we have absolutely no style-related expectations to our minified file,
we do care that it's valid ES 5.1. This is now verified.

Fixes gh-3075
Ref gh-4594
Closes gh-4598
roytoo/jquery,roytoo/jquery,jquery/jquery,roytoo/jquery,jquery/jquery,jquery/jquery