LONDON—Even the world’s best players are not immune to crippling nerves as Iga Swiatek discovered when her Wimbledon dreams were turned to dust in a 7–5, 6–7(5), 6–2 quarter-final defeat by Ukrainian wildcard Elina Svitolina on Tuesday. Svitolina, who returned to the tour in April after giving birth to her daughter last October, might have…