Implementation class that handles Mozilla rendering issues.

class CaptionPanelImplMozilla extends CaptionPanelImpl {

 void setSafeCaption(dart_html.FieldSetElement fieldset, dart_html.Element legend, SafeHtml caption) {
   setCaption(fieldset, legend, caption.asString(), true);
 }

 void setCaption(dart_html.FieldSetElement fieldset, dart_html.Element legend, String caption, [bool asHtml = true]) {
   fieldset.style.display = "none";
   super.setCaption(fieldset, legend, caption, asHtml);
   fieldset.style.display = "";
 }
}