1. @DomName('DOMTokenList.add')
  2. @DocsEditable()
  3. @Experimental()
void add(String tokens)

Source 

@DomName('DOMTokenList.add')
@DocsEditable()
@Experimental() // untriaged
void add(String tokens) =>
    _blink.BlinkDOMTokenList.instance.add_Callback_1_(this, tokens);