lingering step 2 of the test rename overhaul: make await tests also a directory

frog/tests/await/initializer_negative_test.dart

Index: frog/tests/await/initializer_negative_test.dart
diff --git a/frog/tests/await/initializer_negative_test.dart b/frog/tests/await/initializer_negative_test.dart
index 9a06aaddf7d36344ee99dc6824c97423ad339161..f068b67464edc0a6688bb2edd980bee788a25ec2 100644
--- a/frog/tests/await/initializer_negative_test.dart
+++ b/frog/tests/await/initializer_negative_test.dart
@@ -2,6 +2,11 @@
 // 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.
 
+// The next line is used to tell test.dart that this test is run by invoking
+// awaitc.dart and passing this file as an argument (e.g. frog
+// frog/await/awaitc.dart test.dart):
+// VMOptions=frog/await/awaitc.dart
+
 // Illegal to use await in initializers.
 #import("await_test_helper.dart");