window: Don't take a reference on 'toolbar'
VirtViewerTimedRevealer now derives from GtkEventBox/GtkContainer, so
it follows GTK+ conventions and takes ownership of the floating ref on
'toolbar'. Since VirtViewerWindow and VirtViewerTimedRevealer will have
the same lifespan, we don't need to own a reference on toolbar in
VirtViewerWindow.
Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>
Acked-by: Fabiano FidĂȘncio <fidencio@redhat.com>