Give non-isolated windows a tabIndex for selection holding
Give non-isolated windows a tabIndex for selection holding

Isolated windows have this already but at the time we had no
use case for non-isolated windows to have it.

Change-Id: I62e11011b80b806a60e81b062e8cbfd46b3d2c7d

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui