getComputedTiming();

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

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

  // -Infinity delay + Infinity active duration + -Infinity end