X17 XCLUSIVE - BRITNEY DINES WITH MEL GIBSON!

We caught up with Britney tonight at Romanov Russian restaurant in Studio City tonight -- but it appears NOT to have been just any dinner ... A waiter at the restaurant told our photogs that Britney dined with Mel Gibson! We're not sure why the two former Malibu Serra Retreat neighbors would meet up for dinner -- Is Mel casting for "The Passion of the Christ, Part 2?" Were they discussing his film "Paparazzi?" Or maybe Gibson's on a mission to save Brit. He was quoted, in December 2006, as having some kind words for Brit -- Read the quotation, after the jump ... "I feel compassion for someone like Britney, for instance. She never gets a moment. She's, like, dogged all the time and followed and she's trying to have a life. Your heart goes out to her because I'm positive that, at her core, she's a good woman."