Make sure disambiguation popup parent is a elementary widget.

Make sure disambiguation popup parent is a elementary widget.

Elementary widgets require to have other elm widgets as their parents.
When this requirement is not met elementary focus chain is broken.
Since disambiguation popup uses elementary widgets we need to make sure
the parent we give it is also an elm widget.

This patch fixes a couple of EFL runtime errors seen on Tizen 2.4 mobile
target during ubrowser/efl_webview_app startup.

Change-Id: I36a9b9920f5ca61aedc7ef1ca1420a04cbc2f6f8
Signed-off-by: Piotr Tworek <p.tworek@samsung.com>