Use MSGBOX constants

data/maps/ThreeIsland_BondBridge/scripts.inc

@@ -2,9 +2,9 @@ ThreeIsland_BondBridge_MapScripts:: @ 8168776
 	.byte 0
 
 ThreeIsland_BondBridge_EventScript_168777:: @ 8168777
-	msgbox gUnknown_818A210, 3
+	msgbox gUnknown_818A210, MSGBOX_SIGN
 	end
 
 ThreeIsland_BondBridge_EventScript_168780:: @ 8168780
-	msgbox gUnknown_818A223, 3
+	msgbox gUnknown_818A223, MSGBOX_SIGN
 	end