writeSummaryToFile method Null safety

Implementation

@Deprecated(
  'Use TimelineSummary.writeTimelineToFile. '
  'This feature was deprecated after v2.1.0-13.0.pre.'
)
Future<void> writeSummaryToFile(
  String traceName, {
  String? destinationDirectory,
  bool pretty = false,
}) async {
  destinationDirectory ??= testOutputsDirectory;
  await _writeSummaryToFile(traceName, destinationDirectory: destinationDirectory, pretty: pretty);
}