dart2js: run dartfmt on tests

tests/compiler/dart2js_extra/if_test.dart

 // Copyright (c) 2011, 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:expect/expect.dart";
 
 int if1() {
   if (true) {
     return 499;
   }
@@ skipping 21 matching lines @@
   if (true) {
     return 499;
   } else {
     return 42;
   }
 }
 
 int if5() {
   if (true) {
     if (false) return 42;
-  } else {
-  }
+  } else {}
   return 499;
 }
 
 int if6() {
   if (true) {
     if (false) return 42;
   }
   return 499;
 }
 
 void main() {
   Expect.equals(499, if1());
   Expect.equals(499, if2());
   Expect.equals(499, if3());
   Expect.equals(499, if4());
   Expect.equals(499, if5());
   Expect.equals(499, if6());
 }