bonzo doesn't specialcase "required" attr

[x-yuri]

By that I mean, that required attr behaves as , e.g., checked one:

<input id="i1">   <!-- document.getElementById('i1').required === false -->
<input id="i2" required>   <!-- document.getElementById('i2').required === true -->
<input id="i3" required="required">   <!-- document.getElementById('i3').required === true -->