String challenge

Source 

@DomName('HTMLKeygenElement.challenge')
@DocsEditable()
String get challenge => _blink.BlinkHTMLKeygenElement.instance.challenge_Getter_(this);
void challenge=(String value)

Source 

@DomName('HTMLKeygenElement.challenge')
@DocsEditable()
set challenge(String value) => _blink.BlinkHTMLKeygenElement.instance.challenge_Setter_(this, value);