They seem to be running late. Hundreds of conspiracy theorists gathered at the AT&T Discovery Plaza in Dallas to await the arrival of former President Donald Trump and John F. Kennedy Jr., whom they expected to announce an unlikely campaign for the White House around 12:30 p.m. Tuesday. As of late afternoon, those optimists were still waiting. Kennedy’s absence was likely due to the 1999 plane crash in which he died. His father, former President John F. Kennedy, was fatally shot in November 1963 at the downtown Dallas locale where supporters had gathered. The event had been promoted through the...