Fixes bartender drink slide spill

Forces drink throw call to check for bartender throwing before spilling contents. Feels like a lazy fix, but it works.

code/modules/reagents/reagent_containers.dm

@@ -156,7 +156,8 @@
 		if(QDELETED(src))
 			return
 
-	reagents.clear_reagents()
+	if (!bartender_check(target)) // Needs to check for Bartender Slide before spilling.
+		reagents.clear_reagents() // Clear reagents of thrown container.
 
 //melts plastic beakers
 /obj/item/reagent_containers/microwave_act(obj/machinery/microwave/M)