Jack Schlossberg, the grandson of former President John F. Kennedy, is blasting a measure from House Republicans that would rename the Kennedy Center’s famed Opera House in honor of Melania Trump. “A nation reveals itself not only by the men it produces — but also by the men it honors, the men it remembers,” Schlossberg, quoting his grandfather, wrote in a Tuesday post on Instagram. “JFK believed the arts made our country great and could be our most effective weapon in the fight for civil rights and against authoritarian governments around the world,” Schlossberg, a vocal critic of President Trump,...