Extended Stopwatch class

StopWatch.dart

//////////Usage of the StopWatch class //////////////////////

void main() {
  var stopwatch = new StopWatch();
  stopwatch.start();
  stopwatch.milliseconds = 10000; //10 seconds have passed
  print(stopwatch.elapsedDuration);
  stopwatch.stop();
}


//////////////////////////////////////////////////////////////////////
// StopWatch class //
/////////////////////////////////////////////////////////////////////

class StopWatch extends Stopwatch{
  int _starterMilliseconds = 0;
  
  StopWatch();
  
  get elapsedDuration{
    return Duration(
      microseconds: 
      this.elapsedMicroseconds + (this._starterMilliseconds * 1000)
    );
  }
  
  get elapsedMillis{
    return this.elapsedMilliseconds + this._starterMilliseconds;
  }
  
  set milliseconds(int timeInMilliseconds){
    this._starterMilliseconds = timeInMilliseconds;
  }
  
}