Make timer test more robust.

tests/lib/async/timer_regress22626_test.dart

Index: tests/lib/async/timer_regress22626_test.dart
diff --git a/tests/lib/async/timer_regress22626_test.dart b/tests/lib/async/timer_regress22626_test.dart
index 483b93382f6535203107efc3dd897c39bae9cdc4..810be7cb656cec3c3dd6ee0c5f44eea57b00e4b5 100644
--- a/tests/lib/async/timer_regress22626_test.dart
+++ b/tests/lib/async/timer_regress22626_test.dart
@@ -12,7 +12,7 @@ import 'dart:async';
 import 'dart:math';
 import 'package:expect/expect.dart';
 
-int countdown = 10;
+int countdown = 5;
 var rng = new Random(1234);
 
 void test(int delay, int delta) {
@@ -31,5 +31,5 @@ void test(int delay, int delta) {
 }
 
 void main() {
-  test(50, 2);
+  test(200, 2);
 }