dart2js: run dartfmt on tests

tests/compiler/dart2js_extra/mirrors_used_closure_test.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.
 
 library MirrorsTest;
 
 import 'package:expect/expect.dart';
 
 @MirrorsUsed(targets: const ['A.foo', 'B.bar'])
 import 'dart:mirrors';
 
 class A {
   foo() => 42;
   bar() => 499;
 }
 
 class B {
   bar() => 33;
 }
 
 @NoInline()
 @AssumeDynamic()
 confuse(x) => x;
 
 main() {
   var f = [new A(), new B()][confuse(0)].bar;
-  Expect.throws(() => reflect(f).invoke(#call, [], {}),
-                (e) => e is UnsupportedError);
+  Expect.throws(
+      () => reflect(f).invoke(#call, [], {}), (e) => e is UnsupportedError);
 }