Remove frog from the repository.

frog/tests/await/nested_try_catch4_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
-
-// Await within a nested try-catch block, throw happens on await, inner catch
-// has priority.
-
-#import("await_test_helper.dart");
-
-class E1 implements Exception {
-  const E1([msg=null]);
-}
-
-awaitAndThrow(Exception ex) {
-  try {
-    try {
-      final f = errorOf(ex);
-      final t = await f;
-      return 0;
-    } catch (E1 e) {
-      return 1;
-    }
-  } catch (E1 e) {
-    return 2;
-  }
-}
-
-main() {
-  int t = await awaitAndThrow(const E1());
-  Expect.equals(1, t);
-}