Fixes bubble/hull shield generators not updating air zones, update_nearby_tiles() cleanup.

code/modules/shieldgen/emergency_shield.dm

@@ -27,16 +27,6 @@
 	if(!height || air_group) return 0
 	else return ..()
 
-//Looks like copy/pasted code... I doubt 'need_rebuild' is even used here - Nodrak
-/obj/machinery/shield/proc/update_nearby_tiles(need_rebuild)
-	if(!air_master)
-		return 0
-
-	air_master.mark_for_update(get_turf(src))
-
-	return 1
-
-
 /obj/machinery/shield/attackby(obj/item/weapon/W as obj, mob/user as mob)
 	if(!istype(W)) return
 
@@ -357,4 +347,4 @@
 		src.icon_state = malfunction ? "shieldonbr":"shieldon"
 	else
 		src.icon_state = malfunction ? "shieldoffbr":"shieldoff"
-	return
+	return