dart2js: run dartfmt on tests

tests/compiler/dart2js/source_map_deferred_validator_test_file.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 'source_map_deferred_validator_test_lib.dart' deferred as def;
 
 void main() {
   def.loadLibrary().then((_) {
     () {
       var helloClass = new def.HelloClass();
       helloClass.printHello();
     }();
   });
-}
+}