Fix test.aria.widgets.container.dialog.closeOutside.Issue389TestCase

This commit fixes a failing test on Firefox:
 test.aria.widgets.container.dialog.closeOutside.Issue389TestCase

The regression was caused by 6f4e5e3586e1f1ed7f721bb16fd8ff79fa9a2c86
along with the following bug in Firefox:
when inserting the java robot applet while a field is focused,
the field stays focused but no longer reacts when typing.