generateDOMAsyncElement method
      
T?
generateDOMAsyncElement(
    
    
- DOMElement? domParent,
- T? parent,
- DOMAsync domAsync,
- DOMTreeMap<T> treeMap,
- DOMContext<T> ? context,
Implementation
T? generateDOMAsyncElement(DOMElement? domParent, T? parent,
    DOMAsync domAsync, DOMTreeMap<T> treeMap, DOMContext<T>? context) {
  T? templateElement;
  if (domAsync.loading != null) {
    var nodes = DOMNode.parseNodes(domAsync.loading);
    if (nodes.isNotEmpty) {
      DOMNode rootNode;
      if (nodes.length == 1) {
        rootNode = nodes.first;
      } else {
        rootNode = $div(content: nodes);
      }
      templateElement = build(domParent, parent, rootNode, treeMap, context);
    }
  }
  templateElement ??= createElement('template');
  var future = domAsync.resolveFuture!;
  return _generateFutureElementImpl(
      domParent, parent, domAsync, templateElement, future, treeMap, context);
}