 delay
  effect = new KeyframeEffect(null,
    { opacity: [0, 1] },
    { duration: 1,
      delay: -Number.MAX_VALUE, endDelay: -Number.MAX_VALUE,
      iterations: Infinity });
  effect.getComputedTiming();

  // -Infinity delay + finite active duration
  effect = new KeyframeEffect(null,
    { opacity: [0, 1] },
    { duration: 1, delay: -Number.MAX_VALUE, iterations: 1 });
  effect.getComputedTiming();

  // -Infinity end delay + finite active duration
  effect = new KeyframeEffect(null,
    { opacity: 