chromium/src/third_party/blink/web_tests/external/wpt/html/user-activation/resources/utils.js

function delayByFrames(f, num_frames) {
  function recurse(depth) {
    if (depth == 0)
      f();
    else
      requestAnimationFrame(() => recurse(depth-1));
  }
  recurse(num_frames);
}