BRISTOL, Tenn. — Jimmie Johnson has been nothing short of dominant during his 14-year NASCAR Sprint Cup Series career, winning a mind-boggling six titles and 72 races.But that dominance hasn’t extended to Bristol Motor Speedway. Johnson won a Cup race in Bristol in 2010, but heading into today’s Food City 500 in Support of Steve Byrnes, the frustrating days in Thunder Valley have far outweighed the good ones for Johnson and his No.