wayland: Don't continue showing if xdg_popup creation failed

wayland: Don't continue showing if xdg_popup creation failed

We don't create a grabbing popup if it's not the top most one, as that
is a protocol violation, and complain if anything attempts to do it.
What we didn't do is handle this gracefully in the code that tries to
create said popup.

Fix this by dropping the attempt to show the popup on the floor, instead
of setting various state making it look like it succeeded. This won't
actually fix anything, but it'll result in a bit more accurate warnings
logged, as the state more correctly corresponds to the reality.