Make sure the tested QVideoWidget has a valid size.
Since 7b63c45d in qtbase, native widgets are required to have a valid
size to be shown. This test relies on qWaitForWindowExposed() to work
correctly, which means the widget must be shown and thus must have
a valid size.
Change-Id: I13bc1536d788d9ba56b4dcbf0c60851b5634be9e
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>
f69a051675