The position child property is problematic, since it
requires us to emit notification for all children when
inserting a child early in the list of children.
Remove the property from all ui files.
This test was failing in continuous, where the tests are running
in a VM with disabled animations. Make the test adapt to that
situation by changing the rui on the fly if we find that animations
are disabled.
This fixes shadows that are animated not updating the clip of the widget
they are drawn on. An example of this are the buttons in the CSS shadows
example in gtk-demo.
Reftest included
