test.aria.utils.cfgframe.AriaWindowTest failing on IE 8

Commit 2c1141e33deb90e8a5c5cd10676d87b486dd22c4 makes the following test fail on IE 8: `test.aria.utils.cfgframe.AriaWindowTest`. It only happens on a true IE 8 (not on IE 11 in IE 8 mode).

The issue comes from an "Unspecified error" raised when trying to read `Aria.$window.document.activeElement`. This pull request surrounds that piece of code by a try ... catch.