compareNodeIframe(node, prevNode, ifr) {
    const compCurr = node.compareDocumentPosition(ifr),
      prev = Node.DOCUMENT_POSITION_PRECEDING;
    if (compCurr & prev) {
      if (prevNode !== null) {
        const compPrev = prevNode.compareDocumentPosition(ifr),
          after = Node.DOCUMENT_POSITION_FOLLOWING;
        if (compPrev & after) {
          return true;
        }
      } else {
        return true;
      }
    }
    return false;
  }
Checks if an iframe occurs between two nodes, more specifically if an
iframe occurs before the specified node and after the specified prevNode
@param {HTMLElement} node - The node that should occur after the iframe
@param {HTMLElement} prevNode - The node that should occur before the
iframe
@param {HTMLElement} ifr - The iframe to check against
@return {boolean}
@access protected