Revert "dbus: fix nil notifications (#2180)"

This reverts commit 7519c6966a.

lib/naughty/core.lua

@@ -411,12 +411,6 @@ function naughty.getById(id)
     end
 end
 
---- Increase notification ID by one
-function naughty.get_next_notification_id()
-  counter = counter + 1
-  return counter
-end
-
 --- Install expiration timer for notification object.
 -- @tparam notification notification Notification object.
 -- @tparam number timeout Time in seconds to be set as expiration timeout.

lib/naughty/dbus.lua

@@ -191,11 +191,9 @@ capi.dbus.connect_signal("org.freedesktop.Notifications",
                 end
                 args.freedesktop_hints = hints
                 notification = naughty.notify(args)
-                if notification ~= nil then
-                    return "u", notification.id
-                end
+                return "u", notification.id
             end
-            return "u", naughty.get_next_notification_id()
+            return "u", "0"
         elseif data.member == "CloseNotification" then
             local obj = naughty.getById(appname)
             if obj then