static WebTree webTree_sortChildren(WebTree tree) {
  sortList(tree.children, makeComparator(func(Pair<WebNode, WebTree> a, Pair<WebNode, WebTree> b) {
    int i = stdCompare(web_text(a.a), web_text(b.a));
    if (i != 0) ret i;
    ret stdCompare(web_text(a.b.node), web_text(b.b.node));
  }));
  for (Pair<WebNode, WebTree> p : tree.children)
    webTree_sortChildren(p.b);
  ret tree;
}