dart2dart: Test cases for better code coverage in dart_tree rewritings.

tests/language/if_flatten2_test.dart

-// Copyright (c) 2014, 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.
-
-import 'package:expect/expect.dart';
-
-check_true_true(x, y) {
-  if (x) {
-    if (y) {
-      return true;
-    }
-  }
-  return false;
-}
-
-check_false_true(x, y) {
-  if (x) {
-
-  } else {
-    if (y) {
-      return true;
-    }
-  }
-  return false;
-}
-
-check_true_false(x, y) {
-  if (x) {
-    if (y) {
-
-    } else {
-      return true;
-    }
-  }
-  return false;
-}
-
-check_false_false(x, y) {
-  if (x) {
-
-  } else {
-    if (y) {
-
-    } else {
-      return true;
-    }
-  }
-  return false;
-}
-
-
-main() {
-  Expect.equals(true, check_true_true(true, true));
-  Expect.equals(false, check_true_true(true, false));
-  Expect.equals(false, check_true_true(false, true));
-  Expect.equals(false, check_true_true(false, false));
-
-  Expect.equals(false, check_true_false(true, true));
-  Expect.equals(true, check_true_false(true, false));
-  Expect.equals(false, check_true_false(false, true));
-  Expect.equals(false, check_true_false(false, false));
-
-  Expect.equals(false, check_false_true(true, true));
-  Expect.equals(false, check_false_true(true, false));
-  Expect.equals(true, check_false_true(false, true));
-  Expect.equals(false, check_false_true(false, false));
-
-  Expect.equals(false, check_false_false(true, true));
-  Expect.equals(false, check_false_false(true, false));
-  Expect.equals(false, check_false_false(false, true));
-  Expect.equals(true, check_false_false(false, false));
-}