makes w_class use defines (#9848)

code/modules/assembly/assembly.dm

@@ -4,7 +4,7 @@
 	icon = 'icons/obj/assemblies/new_assemblies.dmi'
 	icon_state = ""
 	flags = CONDUCT
-	w_class = 2.0
+	w_class = ITEMSIZE_SMALL
 	matter = list(DEFAULT_WALL_MATERIAL = 100)
 	throwforce = 2
 	throw_speed = 3

code/modules/assembly/bomb.dm

@@ -3,7 +3,7 @@
 	icon = 'icons/obj/tank.dmi'
 	item_state = "assembly"
 	throwforce = 5
-	w_class = 3.0
+	w_class = ITEMSIZE_NORMAL
 	throw_speed = 2
 	throw_range = 4
 	flags = CONDUCT | PROXMOVE

code/modules/assembly/holder.dm

@@ -5,7 +5,7 @@
 	item_state = "assembly"
 	flags = CONDUCT | PROXMOVE
 	throwforce = 5
-	w_class = 2.0
+	w_class = ITEMSIZE_SMALL
 	throw_speed = 3
 	throw_range = 10
 

code/modules/assembly/shock_kit.dm

@@ -5,7 +5,7 @@
 	var/obj/item/clothing/head/helmet/part1 = null
 	var/obj/item/device/radio/electropack/part2 = null
 	var/status = 0
-	w_class = 5.0
+	w_class = ITEMSIZE_HUGE
 	flags = CONDUCT
 
 /obj/item/assembly/shock_kit/Destroy()