tion enqueueStep4() {
    target1.scrollIntoView();
    requestAnimationFrame(() => {
      requestAnimationFrame(() => {
        runStep4();
      });
    });
  }

  // Verify that all elements received not intersecting event, except
  // target4, which remains not intersecting.
  function runStep4() {
    const step = arguments.callee.name;
    t.step(() => {
      assert_equals(entries.length, 3, step);
      for (let i = 0; i < entries.length; ++i) {
        assert_true(entries[i].isIntersecting);
     