code: function getSiblingNode(node) {
    while (node) {
      if (node.nextSibling) {
        return node.nextSibling;
      }
      node = node.parentNode;
    }
  }
docs: Get the next sibling within a container. This will walk up the
  DOM if a node's siblings have been exhausted.
  
  @param {DOMElement|DOMTextNode} node
  @return {?DOMElement|DOMTextNode}