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

tests/language/rewrite_nested_if3_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';
 
+baz() {}
+
 check_true_true(x, y) {
   if (x) {
     if (y) {
       return true;
     }
   }
+  baz();
   return false;
 }
 
 check_false_true(x, y) {
   if (x) {
 
   } else {
     if (y) {
       return true;
     }
   }
+  baz();
   return false;
 }
 
 check_true_false(x, y) {
   if (x) {
     if (y) {
 
     } else {
       return true;
     }
   }
+  baz();
   return false;
 }
 
 check_false_false(x, y) {
   if (x) {
 
   } else {
     if (y) {
 
     } else {
       return true;
     }
   }
+  baz();
   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));
 }