Fixes bloodstains getting stuck (shiptest-ss13#2456)

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![image](https://github.com/shiptest-ss13/Shiptest/assets/45698967/0cfb95d1-673a-47a9-94dc-af3fba94430a)
As shown in image, bloodstains were getting stuck in the shape of the
first item to draw blood that round

Ports the rest of
[https://github.com/BeeStation/BeeStation-Hornet/pull/3111](url), which
seems to fix it.

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Blub :)

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:cl:
fix: bloodstains no longer steal the shape of the first item to spill
blood
/:cl:

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code/datums/components/forensics.dm

@@ -190,4 +190,6 @@
 		return
 	if(!length(blood_DNA))
 		return
-	parent.AddElement(/datum/element/decal/blood, _color = get_blood_dna_color(blood_DNA))
+	if(isitem(parent))
+		var/obj/item/I = parent
+		I.AddElement(/datum/element/decal/blood, initial(I.icon) || I.icon, initial(I.icon_state) || I.icon_state, _color = get_blood_dna_color(blood_DNA))

code/datums/elements/decals/blood.dm

@@ -12,27 +12,15 @@
 	return ..()
 
 /datum/element/decal/blood/generate_appearance(_icon, _icon_state, _dir, _layer, _color, _alpha, source)
-	var/obj/item/I = source
-	if(!_icon)
-		_icon = 'icons/effects/blood.dmi'
-	if(!_icon_state)
-		_icon_state = "itemblood"
+	if(!_icon || !_icon_state)
+		return FALSE
 	if(!_color)
 		_color = COLOR_BLOOD
-	var/item_icon = I.icon
-	var/item_icon_state = I.icon_state
-	var/static/list/blood_splatter_appearances = list()
-	//try to find a pre-processed blood-splatter. otherwise, make a new one
-	var/index = "[REF(item_icon)]-[item_icon_state]"
-	pic = blood_splatter_appearances[index]
-
-	if(!pic)
-		var/icon/blood_splatter_icon = icon(I.icon, I.icon_state, null, 1)		//we only want to apply blood-splatters to the initial icon_state for each object
-		blood_splatter_icon.Blend("#fff", ICON_ADD) 			//fills the icon_state with white (except where it's transparent)
-		blood_splatter_icon.Blend(icon(_icon, _icon_state), ICON_MULTIPLY) //adds blood and the remaining white areas become transparant
-		pic = mutable_appearance(blood_splatter_icon, initial(I.icon_state))
-		pic.color = _color
-		blood_splatter_appearances[index] = pic
+	var/icon/blood_splatter_icon = icon(_icon, _icon_state, , 1)		//we only want to apply blood-splatters to the initial icon_state for each object
+	blood_splatter_icon.Blend("#fff", ICON_ADD) 			//fills the icon_state with white (except where it's transparent)
+	blood_splatter_icon.Blend(icon('icons/effects/blood.dmi', "itemblood"), ICON_MULTIPLY) //adds blood and the remaining white areas become transparant
+	pic = mutable_appearance(blood_splatter_icon)
+	pic.color = _color
 	return TRUE
 
 /datum/element/decal/blood/proc/get_examine_name(datum/source, mob/user, list/override)