The execution of an async* should only be scheduled when the stream is

tests/language/asyncstar_concat_test.dart

Index: tests/language/asyncstar_concat_test.dart
diff --git a/tests/language/await_not_started_immediately_test.dart b/tests/language/asyncstar_concat_test.dart
similarity index 50%
copy from tests/language/await_not_started_immediately_test.dart
copy to tests/language/asyncstar_concat_test.dart
index 035885e09c23480054e0dcf5c31ff63ca3a35963..aeb1361cd85fdcc35bf1fd466b161c2462befc4e 100644
--- a/tests/language/await_not_started_immediately_test.dart
+++ b/tests/language/asyncstar_concat_test.dart
@@ -2,21 +2,28 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// Test that an async function does not start immediately.
-
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 
-var x = 0;
+range(start, end) async* {
+  for (int i = start; i < end; i++) {
+    yield i;
+  }
+}
+
+concat(a, b) async* {
+  yield* a;
+  yield* b;
+}
 
-foo() async {
-  x++;
-  await 1;
-  x++;
+test() async {
+  Expect.listEquals([1, 2, 3, 11, 12, 13],
+                    await concat(range(1, 4), range(11, 14)).toList());
 }
 
-void main() {
+main() {
   asyncStart();
-  foo().then((_) => Expect.equals(2, x)).whenComplete(asyncEnd);
-  Expect.equals(0, x);
+  test().then((_) {
+    asyncEnd();
+  });
 }