Chris Brown and Kristii have been blazing up dance floors all summer with “Lightning,” their energetic dance track that mixes rap with R&B pop. This weekend, Kristii performs it live at two area performances: the first, on Saturday night at The Monster. Then, on Monday, she takes the stage at Promo Only’s Summer Sessions in Atlantic City. Kristii first broke onto the Billboard club charts in January with “Recovery,” a song that climbed to the...