Orca code freeze break request (yeah, one more)

[Joanmarie Diggs <jdiggs igalia com>]

Greetings release team!

I have been testing our shiny new gnome-software with Orca and filing
bugs based on my findings for Matthias. Turns out one of the bugs was
mine. (Oops).

It's another one-line safe fix which causes Orca to present the presence
of a necessary GtkButton so users know they can remove/install the
selected item.

If y'all would be so kind as to grant me a(nother) freeze break, I'd
appreciate it.

https://bugzilla.gnome.org/show_bug.cgi?id=708497

--joanie