A conservative social media provocateur confronted District Attorney Larry Krasner in a Philadelphia park this past week, prompting an early-morning spat between the two that included the prosecutor calling President Donald Trump a “fascist” and telling the social media activist to “put down Mein Kampf.” The back-and-forth between Krasner and Frank Scales, 22, who runs the account SurgePhilly on TikTok, is the second time the pair have quarreled in recent weeks. Scales shouted at the district attorney during a recent town hall and organized a protest against Krasner earlier this month. But the videos that Scales posted to social media...