Katy Perry's 'Witness': Album Review Katy Perry boldly explores club sub-genres on her banger-heavy new album. MORE >> Here’s a special treat. Katy Perry’s demo of “Passenger,” a song that later graced Britney Spears’ Britney Jean LP, has… (in post Katy Perry’s Demo Of Britney Spears’ “Passenger” Is Here & It’s Magnificent from Idolator. More by this artist at )