void forEach(
void callback(String value, String key, Headers map),
[Object thisArg]
)

Not documented.

Source

void forEach(HeadersForEachCallback callback, [Object thisArg]) {
  if (thisArg != null) {
    _blink.BlinkHeaders.instance.forEach_Callback_2_(unwrap_jso(this), unwrap_jso(callback), thisArg);
    return;
  }
  _blink.BlinkHeaders.instance.forEach_Callback_1_(unwrap_jso(this), unwrap_jso(callback));
  return;
}