When a QObject subclass (widgets, etc.) are provided a parent, then
ownership of that object is passed to the parent. Similarly, objects
added to a QLayout are owned by the layout.
Thus, do not store these objects in an OwnPtr.
The default behavior of QPushButton is much closer to what we want from
a drop-down menu, as shown in the QPushButton::setMenu documentation:
https://doc.qt.io/qt-6/qpushbutton.html#setMenu
This also results in much less of a "squished" look than before.
This will help a lot with developing chromes for different UI frameworks
where we can see which helper classes and processes are really using Qt
vs just using it to get at helper data.
As a bonus, remove Qt dependency from WebDriver.
