Xavier Becerra and Tom Steyer, the two Democrats who emerged as narrow frontrunners in the race for California governor after the implosion of Eric Swalwell , were on the defensive in Tuesday night’s CNN debate. Rivals — Republican and Democrat — attacked Becerra and Steyer throughout the evening, as they jockey for position in the “jungle primary.” Only two candidates will advance, regardless of party. The contest was fairly even, until Katie Porter — who had started strong — scored a spectacular own goal by bringing up her own temperament as an issue. The debate then pivoted to Chad Bianco , who took the spotlight for several minutes. Xavier Becerra and Tom Steyer, the two Democrats who emerged as narrow frontrunners in the race for California governor after the implosion of Eric Swalwell, were on the defensive in Tuesday night’s CNN debate.…