“Shuffle Sia’s "Chandelier" into a playlist of songs she’s written for pop stars bigger than herself, and at first you might think it was yet another surefire hit gifted away by the uncommonly prolific Australian singer. Is that Rihanna’s accent on the first verse? Is the call to have a drink Lea Michele’s attempt at a party rock anthem? But then, the chorus hits and Sia’s voice blasts off, the swe”