OMAHA, Neb.—America’s biggest swimming stars shined brightly on the next-to-last night of the Olympic trials. Their only complaint? Both wanted to go a bit faster Saturday. Caeleb Dressel added another event to his Tokyo program, powering to a dominating victory in the 100-meter butterfly. Katie Ledecky blew away the field in the 800 freestyle, winning by more than 5 seconds in a race where the battle for second provided the only drama. Ledecky locked up her fourth individual race at the Olympics with a time of 8 minutes, 14.62 seconds, adding to her victories in the 200, 400 and 1,500 free. Leading right from the start, Ledecky was essentially racing herself. She started out under world-record pace but tailed off when it quickly became clear no one could beat her. “It’s challenging,” she said of being so far ahead of the field. “Sometimes I feel like I’m going faster than …