Remove frog from the repository.

frog/tests/await/single_await_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.
-
-// 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
-
-// Simple test that transforms the await keyword used at the top-level of a
-// function body.
-
-#import("await_test_helper.dart");
-
-main() {
-  final f = futureOf(3);
-  final x = await f;
-  Expect.equals(3, x);
-}
-
-// This is roughly equivalent to:
-// main() {
-//   final _ret = new Completer();
-//   final f = futureOf(3);
-//   f.then((x) {
-//     Expect.equals(3, x);
-//     _ret.complete(null);
-//   });
-//   Futures.propagateError(f, _ret);
-//   return _ret.future;
-// }