appendToPrevious(node) {
    return node.previousSibling ? dom.appendChildNodes(node.previousSibling, [node]) : this.wrapList([node], 'LI');
  }
@method appendToPrevious

Appends list to previous list item, if
none exist it wraps the list in a new list item.

@param {HTMLNode} ListItem
@return {HTMLNode}