Merge pull request #5190 in master
Add "role" to $validGlobalAttributes

See http://www.w3.org/html/wg/drafts/html/master/dom.html#wai-aria
Merge branch 'patch-1' of https://github.com/glen-84/zf2 into PR-5276

* 'patch-1' of https://github.com/glen-84/zf2:
  Add "role" to $validGlobalAttributes