title: element.dataset in Internet Explorer
body: <p>I need a way to list the <code>data-*</code> attributes of an element.  I would use <code>Object.keys(element.dataset)</code> but IE 9.0 doesn't have <code>dataset</code> support.  How should I do this in a way that works for IE 9.0 (and Chrome, Firefox, Safari)?</p>