When we drop our weak ref, we better reset the pointer too.

This was meant to go into 678eb8ab76bd.

maplistmodel: Fix items-changed emission

See merge request GNOME/gtk!4872

Add some tests for adding and removing items.

We were modifying the removed value before passing
it to the items-changed signal, so we always ended
up with removed == 0 in our signal emission, instead
of passing the original value on, as we should.

Pointed out in !4870

pango_font_description_to_css: Handle numeric weight

See merge request GNOME/gtk!4871

The PangoWeight enum agrees with the numeric values
we use here, so we can do this without a switch and
support numeric weight values at the same time.

pango_font_description_to_css: Add extra-expanded

See merge request GNOME/gtk!4869