Add test for bug in dart2js.

tests/compiler/dart2js/is_inference_test.dart

 // Copyright (c) 2012, 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("compiler_helper.dart");
 
 final String TEST_IF = @"""
 test(param) {
   if (param is int) {
     param = param + 42;
@@ skipping 46 matching lines @@
     return param + 53;
   } else {
     param = param + 42;
   }
   return param;
 }
 """;
 
 compileAndTest(String code) {
   String generated = compile(code, 'test');
-  print(code);
-  print(generated);
   RegExp validAdd = new RegExp("$anyIdentifier \\+ 42");
   RegExp invalidAdd = new RegExp("$anyIdentifier \\+ 53");
   Expect.isTrue(validAdd.hasMatch(generated));
   Expect.isFalse(invalidAdd.hasMatch(generated));
 }
 
 main() {
   compileAndTest(TEST_IF);
   compileAndTest(TEST_IF_ELSE);
   compileAndTest(TEST_IF_RETURN);
   compileAndTest(TEST_IF_NOT_ELSE);
   compileAndTest(TEST_IF_NOT_RETURN);
   compileAndTest(TEST_IF_NOT_ELSE_RETURN);
 }