Fix tests that use a 0-length timeout.

test/runner/runner_test.dart

Index: test/runner/runner_test.dart
diff --git a/test/runner/runner_test.dart b/test/runner/runner_test.dart
index 8a69547cb25321cdd2c3b2616dabf1a0bed0b8d1..493f8b621fc27e06dcab8029be5ed6db8f873da2 100644
--- a/test/runner/runner_test.dart
+++ b/test/runner/runner_test.dart
@@ -402,8 +402,11 @@ import 'dart:async';
 import 'package:test/test.dart';
 
 void main() {
-  test("fail", () => throw 'oh no', onPlatform: {
-    "vm": new Timeout(new Duration(seconds: 0))
+  test("fail", () async {
+    await new Future.delayed(Duration.ZERO);
+    throw 'oh no';
+  }, onPlatform: {
+    "vm": new Timeout(Duration.ZERO)
   });
 }
 ''').create();
@@ -509,7 +512,10 @@ import 'dart:async';
 import 'package:test/test.dart';
 
 void main() {
-  test("fail", () => throw 'oh no');
+  test("fail", () async {
+    await new Future.delayed(Duration.ZERO);
+    throw 'oh no';
+  });
 }
 ''').create();