Fix NPE in DocumentOutlinePage

DocumentOutlinePage throws a NPE when the caret is positioned before or
after the root element, hence the selected is 'null'.

Change-Id: Id6f66739a0bb877c2fa1eccf31cc400c274ccce1
Signed-off-by: Carsten Hiesserich <carsten.hie@gmail.com>
1 file changed