Application.h includes Widget.h which includes Application.h. I'm not entirely
sure what the semantics are in this case, but avoiding this seems to be the
safer approach. In this case, Widget does not actually use Application, so let's
just remove the unused include.
This apparently was a workaround for escape sequences in GML at some
point (see #4937), but it now literally inserts "\n" and no newline, as
the backslash itself is escaped.
Now that WindowServer broadcasts the system theme using an anonymous
file, we need clients to pledge "recvfd" so they can receive it.
Some programs keep the "shared_buffer" pledge since it's still used for
a handful of things.
