void forEach(FontFaceSetForEachCallback callback(FontFace fontFace, FontFace fontFaceAgain, FontFaceSet set), [Object thisArg])

Source 

void forEach(FontFaceSetForEachCallback callback, [Object thisArg]) {
  if (thisArg != null) {
    _blink.BlinkFontFaceSet.instance.forEach_Callback_2_(unwrap_jso(this), unwrap_jso((fontFace, fontFaceAgain, set) => callback(wrap_jso(fontFace), wrap_jso(fontFaceAgain), wrap_jso(set))), thisArg);
    return;
  }
  _blink.BlinkFontFaceSet.instance.forEach_Callback_1_(unwrap_jso(this), unwrap_jso((fontFace, fontFaceAgain, set) => callback(wrap_jso(fontFace), wrap_jso(fontFaceAgain), wrap_jso(set))));
  return;
}