Ref all cached accessibles before querying them for GetItems
Ref all cached accessibles before querying them for GetItems

It is possible, at least in theory, that querying one accessible could
have the side effect of another accessible being dereferenced. If this
results in the accessible being finalized, then this would likely cause
a crash when potentially iterating over the newly-finalized object.

Hopefully fixes http://bugzilla.gnome.org/show_bug.cgi?id=664822

GNOME/at-spi2-core,GNOME/at-spi2-core,GNOME/at-spi2-core,Distrotech/at-spi2-atk,Distrotech/at-spi2-atk,GNOME/at-spi2-atk