code: function _maybeAddInsertionPoint(node, parent, root) {
      var this$1 = this;
  
      var added;
      var insertionPointTag = root.getInsertionPointTag();
      if (node.nodeType === Node.DOCUMENT_FRAGMENT_NODE &&
        !node.__noInsertionPoint) {
        var c$ = node.querySelectorAll(insertionPointTag);
        for (var i=0, n, np, na; (i<c$.length) && (n=c$[i]); i++) {
          np = tree.Logical.getParentNode(n);
          // don't allow node's parent to be fragment itself
          if (np === node) {
            np = parent;
          }
          na = this$1._maybeAddInsertionPoint(n, np, root);
          added = added || na;
        }
      } else if (node.localName === insertionPointTag) {
        tree.Logical.saveChildNodes(parent);
        tree.Logical.saveChildNodes(node);
        added = true;
      }
      return added;
    }
docs: /* note: parent argument is required since node may have an out
  of date parent at this point; returns true if a <content> is being added