dart2dart: Fix a scoping bug in the translation of loops.

tests/language/while_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.
 // Dart test program for testing while statement.
 
 import "package:expect/expect.dart";
 
 class Helper {
   static int f1(bool b) {
     while (b)
       return 1;
 
     return 2;
   }
 
   static int f2(bool b) {
     while (b) {
       return 1;
     }
     return 2;
   }
 
   static int f3(int n) {
     int i = 0;
     while (i < n) {
       i++;
     }
     return i;
   }
+
+  static int f4() {
+    // Verify that side effects in the condition are visible after the loop.
+    int i = 0;
+    while (++i < 3) {}
+    return i;
+  }
 }
 
 class WhileTest {
   static testMain() {
     Expect.equals(1, Helper.f1(true));
     Expect.equals(2, Helper.f1(false));
     Expect.equals(1, Helper.f2(true));
     Expect.equals(2, Helper.f2(false));
     Expect.equals(0, Helper.f3(-2));
     Expect.equals(0, Helper.f3(-1));
     Expect.equals(0, Helper.f3(0));
     Expect.equals(1, Helper.f3(1));
     Expect.equals(2, Helper.f3(2));
+    Expect.equals(3, Helper.f4());
   }
 }
 
 main() {
   WhileTest.testMain();
 }