dart2js: run dartfmt on tests

tests/compiler/dart2js_extra/deferred_custom_loader_test.dart

 // Copyright (c) 2016, 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:async_helper/async_helper.dart';
 import 'package:expect/expect.dart';
 
 import 'deferred_custom_loader_lib.dart' deferred as def;
 
 void setup() native """
 // In d8 we don't have any way to load the content of the file, so just use
 // the preamble's loader.
 if (!self.dartDeferredLibraryLoader) {
   self.dartDeferredLibraryLoader = function(uri, success, error) {
     var req = new XMLHttpRequest();
     req.addEventListener("load", function() {
       eval(this.responseText);
       success();
     });
     req.open("GET", uri);
     req.send();
   };
 }
 """;
 
-
 runTest() async {
   setup();
   await def.loadLibrary();
   Expect.equals(499, def.foo());
 }
 
 main() {
   asyncStart();
   runTest().then((_) => asyncEnd());
 }