Imagine the moment Best Rock Song winner St. Vincent and Dua Lipa first practiced this extremely good mash-up of their respective hits “Masseduction†and “One Kiss,†ahead of Sunday night’s Grammy Awards, let alone the moment they realized the songs we’re mash-up-able at all. Did they even sleep a wink, aware of the song they were about to pass on to the world? If so, sleep tight, tonight, you mash-up angels. You did great.