Change Future.timeout callback to a named parameter.

tests/lib/async/stream_periodic3_test.dart

Index: tests/lib/async/stream_periodic3_test.dart
diff --git a/tests/lib/async/stream_periodic3_test.dart b/tests/lib/async/stream_periodic3_test.dart
index 7f31d7511e2a5dbf84e8e516ef3b1e37f5a77184..a82e556d98612bbe8b9184985a097ae81c3d1c7e 100644
--- a/tests/lib/async/stream_periodic3_test.dart
+++ b/tests/lib/async/stream_periodic3_test.dart
@@ -8,13 +8,11 @@ library dart.test.stream_from_iterable;
 import "dart:async";
 import '../../../pkg/unittest/lib/unittest.dart';
 
-// The stopwatch is more precise than the Timer. It can happen that
-// the TIMEOUT triggers *slightly* too early on the VM. So we add a millisecond
-// as safetymargin.
+// The stopwatch is more precise than the Timer.
 // Some browsers (Firefox and IE so far) can trigger too early. So we add more
 // margin. We use identical(1, 1.0) as an easy way to know if the test is
 // compiled by dart2js.
-int get safetyMargin => identical(1, 1.0) ? 5 : 1;
+int get safetyMargin => identical(1, 1.0) ? 5 : 0;
 
 main() {
   test("stream-periodic3", () {