Mario Lopez, Tiffani Thiessen Share Touching Tributes to 'Saved By the Bell' Co-Star Dennis Haskins

Mario Lopez and Tiffani Thiessen are remembering their on-screen principal, Dennis Haskins, with touching tributes after the "Saved By The Bell" star's death. Mario -- who played A.C. Slater on "Saved By The Bell" -- says he's "heartbroken to hear…