Migrate block 163 to Dart 2.0.

tests/language_2/unconditional_break.dart

 // Copyright (c) 2013, 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.
 
 // Test to ensure that we get don't exceptions in the SSA verifier when
 // generating phi for the return value of an inlined function that contains a
 // loop that always breaks.
 doWhileBreak() {
   do {
     break;
   } while (true);
 }
 
 main() {
   doWhileBreak();
 }