Ports some hud and update_icon code updates.

code/game/objects/items/defib.dm

@@ -47,8 +47,7 @@
 
 /obj/item/defibrillator/update_icon()
 	update_power()
-	update_overlays()
-	update_charge()
+	return ..()
 
 /obj/item/defibrillator/proc/update_power()
 	if(!QDELETED(cell))
@@ -59,23 +58,20 @@
 	else
 		powered = FALSE
 
-/obj/item/defibrillator/proc/update_overlays()
-	cut_overlays()
+/obj/item/defibrillator/update_overlays()
+	. = ..()
 	if(!on)
-		add_overlay("[initial(icon_state)]-paddles")
+		. += "[initial(icon_state)]-paddles"
 	if(powered)
-		add_overlay("[initial(icon_state)]-powered")
-	if(!cell)
-		add_overlay("[initial(icon_state)]-nocell")
-	if(!safety)
-		add_overlay("[initial(icon_state)]-emagged")
-
-/obj/item/defibrillator/proc/update_charge()
-	if(powered) //so it doesn't show charge if it's unpowered
+		. += "[initial(icon_state)]-powered"
 		if(!QDELETED(cell))
 			var/ratio = cell.charge / cell.maxcharge
 			ratio = CEILING(ratio*4, 1) * 25
 			add_overlay("[initial(icon_state)]-charge[ratio]")
+	if(!cell)
+		. += "[initial(icon_state)]-nocell"
+	if(!safety)
+		. += "[initial(icon_state)]-emagged"
 
 /obj/item/defibrillator/CheckParts(list/parts_list)
 	..()

code/game/objects/items/devices/transfer_valve.dm

@@ -224,7 +224,7 @@
 
 		merge_gases()
 		for(var/i in 1 to 6)
-			addtimer(CALLBACK(src, .proc/update_icon), 20 + (i - 1) * 10)
+			addtimer(CALLBACK(src, /atom/.proc/update_icon), 20 + (i - 1) * 10)
 
 	else if(valve_open && tank_one && tank_two)
 		split_gases()