Standard recipes for brownies have a teaspoon of salt in them. Questions like this one and this one explain that it's only for taste. Can you just put some salt on top after they are baked?
For example, the linked answer might imply that yes you can just sprinkle salt on the baked brownie afterwards. But is that true? I also don't understand the comment about "raw flour". None of the flour should be raw after the brownie is baked!