function hasLowerTabOrder(a, b) {
  // Normalize tabIndexes
  // e.g. in Firefox `<div contenteditable>` has `tabIndex = -1`
  const ati = Math.max(a.tabIndex, 0);
  const bti = Math.max(b.tabIndex, 0);
  return ati === 0 || bti === 0 ? bti > ati : ati > bti;
}
@param {HTMLElement} a
@param {HTMLElement} b
@returns {Boolean}