<!DOCTYPE html>
<html class="reftest-wait">
<head>
<meta charset="UTF-8">
<script>
window.onload = function(){
  let a = document.documentElement.animate(null,
            { duration: 100, iterations: Number.POSITIVE_INFINITY });
  a.startTime = 100000; // Set the start time far in the future
  // Try reversing (this should throw because the target effect end is infinity)
  try { a.reverse(); } catch(e) {}
  // Do something that will trigger a timing update
  a.effect.target = document.createElement("span");
  document.documentElement.className = '';
};
</script>
</head>
</html>
