Taylor Swift, Ariana Grande, Iggy Azalea, Sam Smith, Maroon 5, Pharrell, 5 Seconds of Summer, Calvin Harris, Jessie J, Meghan Trainor, OneRepublic, Rixton, Rita Ora, Shawn Mendes, Charli XCX and Nick Jonas: Catch all the must-see moments from Z100’s Jingle Ball concert Friday, Dec. 12, at Madison Square Garden.