If you’re Donald Trump, you can’t buy publicity like this from his enemies in San Diego yesterday: As hundreds of protesters outside his rally here Friday afternoon chanted obscenities, waved Mexican flags and clashed with police, Donald Trump reveled on stage in the drama his candidacy has created. More: One poster referenced Trump’s wife, who immigrated to the United States from Slovenia: “The Art of the Deal. Deport Melania. Legalize 11 million.” Another: “Trump, Shame of America.” Another: “Jesus would not vote for Trump.” And: “Racist, go home.” As the rally progressed inside, a few protesters — including two women...