Update cache in response to role change notifications
Update cache in response to role change notifications

We update the cache in response to name, description, and parent
property-change signals, but we were missing code to handle signals for
role changes.

https://bugzilla.gnome.org/show_bug.cgi?id=685469

GNOME/at-spi2-core,GNOME/at-spi2-core,GNOME/at-spi2-core