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

frog/tests/await/try_catch10_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
+// Pass VM options to run test through the awaitc compiler:
+// VMOptions=frog/await/awaitc.dart
+
 // Await within a try-catch block, exception should not be caught.
 
 #import("await_test_helper.dart");
 
 class E1 implements Exception {
   const E1([msg=null]);
 }
 
 class E2 implements Exception {
   const E2([msg=null]);
@@ skipping 14 matching lines @@
   throw const E1();
 }
 
 main() {
   try {
     int t = await await_main();
   } catch (e) {
     Expect.isTrue(e is E1);
   }
 }