Jonah Hill, the slimmed-down star of “The Sitter,” is dating Ali Hoffman, daughter of Dustin Hoffman. Sources say both are from LA and “were friends when they were growing up. Jonah is good friends with Ali’s brother, Jake. Dustin discovered Jonah when they were in high school.” Jonah got his break in “I Heart Huckabees,” which starred Dustin. The source added, “Jonah was in Hawaii over the holidays with the Hoffman clan.” Reps didn’t get back to us.