hasTemplate property
Returns true if this node has a DOMTemplate.
Implementation
@override
bool get hasTemplate {
  if (_content != null) {
    for (var node in _content!) {
      if (node.hasTemplate) {
        return true;
      }
    }
  }
  if (_attributes != null) {
    for (var attr in _attributes!.values) {
      if (attr.valueHandler is DOMAttributeValueTemplate) {
        return true;
      }
    }
  }
  return false;
}