dart2js: run dartfmt on tests

tests/compiler/dart2js_extra/mirrors_used_closure_test.dart

Index: tests/compiler/dart2js_extra/mirrors_used_closure_test.dart
diff --git a/tests/compiler/dart2js_extra/mirrors_used_closure_test.dart b/tests/compiler/dart2js_extra/mirrors_used_closure_test.dart
index 12551cfdf26165d1fe20e17da45f72a608d351cc..8f5dc8e7ee8602b3d4632418b7aa167eef7a622a 100644
--- a/tests/compiler/dart2js_extra/mirrors_used_closure_test.dart
+++ b/tests/compiler/dart2js_extra/mirrors_used_closure_test.dart
@@ -24,6 +24,6 @@ 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);
 }