TextInputWidget: Allow maxLength of 0 in JS (matching PHP)
TextInputWidget: Allow maxLength of 0 in JS (matching PHP)

While it's silly, the HTML specs permits it, and we need to be
consistent one way or the other.

http://www.w3.org/TR/html5/forms.html#attr-fe-maxlength

Change-Id: I321310113dca413562885549c9b2fae206163dc6

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui