anchor.diff:    test("events prevent timeout", () {
       Stopwatch sw = new Stopwatch();
       StreamController c = new StreamController();
  -    Stream tos = c.stream.timeout(halfSec, onTimeout: (_) {
  +    Stream tos = c.stream.timeout(twoSecs, onTimeout: (_) {
         int elapsed = sw.elapsedMilliseconds;
         if (elapsed > 250) {
           // This should not happen, but it does occasionally.
  
positive.code:       }
      });
      sw.start();
    });
  
    test("closing prevents timeout", () {
      StreamController c = new StreamController();
      Stream tos = c.stream.timeout(halfSec, onTimeout: (_) {
        fail("Timeout not prevented by close");
      });
      tos.listen((_) {}, onDone: expectAsync0((){}));
  
negative.code:       fail("Timeout not prevented by events");
        throw "ERROR";
      });
      // Start the periodic timer before we start listening to the stream.
      // This should reduce the flakiness of the test.
      int ctr = 200;  // send this many events at 5ms intervals. Then close.
      new Timer.periodic(ms5, (timer) {
        sw.reset();
  