Do not return without mutex unlock
Do not return without mutex unlock

It is not possible to use cache,
after child_added_listener(or toplevel_added_listener) returns by calling
g_return_val_if_fail, without g_rec_mutex_unlock.

https://bugzilla.gnome.org/show_bug.cgi?id=793625

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