Update the baselineOffset when short cutting layout due to an empty
text property.  And allow alterations to the baseline due to images,
font scaling and custom layouts when doing a layout.

Task-number: QTBUG-24303
Change-Id: I5a31a6108cded490fef8b0674e15558ea4e22d6b
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>