EUGENE, Ore.—Sydney McLaughlin looked to her left and saw the numbers “51.90.” Her first thought: “Oh my gosh!” Now, at long last, the 400-meter hurdles world record belongs to her. On Sunday night at U.S. Olympic track trials, McLaughlin finally outraced Dalilah Muhammad to earn the victory, and the record, that Muhammad kept grabbing whenever they met. McLaughlin’s 51.90 was good enough to beat Muhammad by 0.52 seconds. It shattered Muhammad’s old world record by 0.26. “It’s one of those moments you think about and dream about and play in your head that you’ll put it together,” said McLaughlin, who not long ago aligned with coach Bobby Kersee. Her record was the highlight of a day that included other kinds of history. Noah Lyles won the 200 meters to punch his Olympic ticket, then celebrated by kneeling on the track and clasping his hands together: “I just stopped stressing and …