dart2js: run dartfmt on tests

tests/compiler/dart2js/top_level_closure_tree_shake_test.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.
 
 import 'dart:async';
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'compiler_helper.dart';
 
 const String TEST_ONE = r"""
 main() {
   var f = use;
   if (false) {
     // This statement and the use of 'foo' should be optimized away, causing
     // 'foo' to be absent from the final code.
     f(foo);
   }
   f(bar);
 }
 
 foo() => 'Tarantula!';
 bar() => 'Coelacanth!';
 
 use(x) {
   print(x());
 }
 """;
 
-
 main() {
   asyncTest(() => Future.wait([
-      compileAll(TEST_ONE).then((String generated) {
-        Expect.isFalse(generated.contains('Tarantula!'),
-            "failed to remove 'foo'");
-        Expect.isTrue(generated.contains('Coelacanth!'));
-      }),
-  ]));
+        compileAll(TEST_ONE).then((String generated) {
+          Expect.isFalse(
+              generated.contains('Tarantula!'), "failed to remove 'foo'");
+          Expect.isTrue(generated.contains('Coelacanth!'));
+        }),
+      ]));
 }