function isDescendant(older, younger) {
  return (
    !!older.children &&
    typeof older.children !== 'function' &&
    older.children.some(
      child => child === younger || isDescendant(child, younger)
    )
  );
}
Check if a node is a descendant of another node.

@param {!Object} older - Potential ancestor of younger node
@param {!Object} younger - Potential descendant of older node

@return {boolean}