void allowCustomElement(String tagName, {UriPolicy uriPolicy, Iterable<String> attributes, Iterable<String> uriAttributes})

Allow custom elements with the specified tag name and specified attributes.

This will allow the elements as custom tags (such as <x-foo></x-foo>), but will not allow tag extensions. Use allowTagExtension to allow tag extensions.

Source 

void allowCustomElement(String tagName,
    {UriPolicy uriPolicy,
    Iterable<String> attributes,
    Iterable<String> uriAttributes}) {
  var tagNameUpper = tagName.toUpperCase();
  var attrs = attributes
      ?.map /*<String>*/ ((name) => '$tagNameUpper::${name.toLowerCase()}');
  var uriAttrs = uriAttributes
      ?.map /*<String>*/ ((name) => '$tagNameUpper::${name.toLowerCase()}');
  if (uriPolicy == null) {
    uriPolicy = new UriPolicy();
  }

  add(new _CustomElementNodeValidator(
      uriPolicy, [tagNameUpper], attrs, uriAttrs, false, true));
}