I've found such code in html5boilerplate:
/**
 * Address styling not present in IE 7/8/9, Firefox 3, and Safari 4.
 * Known issue: no IE 6 support.
 */
[hidden] {
  display: none;
}
What address? What does it affect? Elements with attribute hidden like following example?
<div hidden></div>
 
     
     
     
    