PHILADELPHIA - Voters in Pennsylvania will cast ballots Tuesday in the Democratic Primary for Philadelphia District Attorney that pits a reform-minded incumbent against a veteran homicide prosecutor, likely deciding the future of the office in the overwhelmingly Democratic city.But Philadelphians will also be casting votes in what many pundits nationally say is the first referendum on whether a wave of prosecutors elected on promises of criminal justice reforms — measures like shorter probation and parole and a curtailing of cash bail that disproportionately keeps poor defendants confined pretrial — can survive a rising tide of gun violence and homicides across the country.Much of the backlash from critics in Philadelphia and in other.