Rania: Hide dropdown menu arrows from primary menu location

By default, if you have nested dropdown menus in the menu assigned to your Primary Menu Location, the Rania theme will display small arrows next to the parent item to indicate a dropdown is living beneath it. It looks like this:

Some users may wish to hide these arrows in the primary menu. Here is what this Code Hack looks like in action:

And here is the code you need to implement it: