In order to make Web Inspector accessible to screen reader users, ARIA roles and states should be used to describe the structure of the DOM tree display. In particular,
roles of "tree", "group" and "tree item" should be utilized. Additionally, aria-expanded state would be used to indicate whether the group of tree items is expanded or collapsed.
For more information, please see: http://www.w3.org/WAI/PF/aria/roles#tree
Forgot to mention that aria-selected state would be used to indicate the currently-selected tree item.
Forward duping to bug 132510 which has more info about the problem.
*** This bug has been marked as a duplicate of bug 132510 ***