decoder property
override
    Returns the decoder of this, converting from List<int> to String.
It may be stateful and should not be reused.
Implementation
Utf8Decoder get decoder {
  // Switch between const objects to avoid allocation.
  return _allowMalformed
      ? const Utf8Decoder(allowMalformed: true)
      : const Utf8Decoder(allowMalformed: false);
}