message: Better return null instead of a zero-length byte array, if JSON is the preferred access mechanism.
diff: // This is a platform hack that allows the
  // stream to return already-parsed JSON.
  //
  - // Return zero bytes immediately. If the caller
  - // knows about this, it will ignore the zero
  - // byte return value.
  + // Return null immediately to indicate no data
  + // is available (end-of-stream). If the caller
  + // knows about this hack, it will ignore the
  + // null return value and check for the JSON
  + // first.
  if (result.response.json !== undefined) {
  this._json = result.response.json;
  - return new Uint8Array(0);
  + return null;
  }
  // Retrieve the raw bytes if available,
  