Fixes armlasers breaking on retract (#498)

code/modules/projectiles/guns/mounted.dm

@@ -11,7 +11,6 @@
 
 /obj/item/weapon/gun/energy/e_gun/advtaser/mounted/dropped()//if somebody manages to drop this somehow...
 	..()
-	src.loc = null//send it to nullspace to get retrieved by the implant later on. gotta cover those edge cases.
 
 /obj/item/weapon/gun/energy/laser/mounted
 	name = "mounted laser"
@@ -25,4 +24,3 @@
 
 /obj/item/weapon/gun/energy/laser/mounted/dropped()
 	..()
-	src.loc = null

code/modules/surgery/organs/augments_arms.dm

@@ -155,7 +155,7 @@
 	desc = "A variant of the arm cannon implant that fires lethal laser beams. The cannon emerges from the subject's arm and remains inside when not in use."
 	icon_state = "arm_laser"
 	origin_tech = "materials=4;combat=4;biotech=4;powerstorage=4;syndicate=3"
-	holder = /obj/item/weapon/gun/energy/laser/mounted
+	contents = newlist(/obj/item/weapon/gun/energy/laser/mounted)
 
 /obj/item/organ/cyberimp/arm/gun/laser/l
 	zone = "l_arm"
@@ -166,7 +166,7 @@
 	desc = "A variant of the arm cannon implant that fires electrodes and disabler shots. The cannon emerges from the subject's arm and remains inside when not in use."
 	icon_state = "arm_taser"
 	origin_tech = "materials=5;combat=5;biotech=4;powerstorage=4"
-	holder = /obj/item/weapon/gun/energy/e_gun/advtaser/mounted
+	contents = newlist(/obj/item/weapon/gun/energy/e_gun/advtaser/mounted)
 
 /obj/item/organ/cyberimp/arm/gun/taser/l
 	zone = "l_arm"