Re-land "Format all multitests"

tests/language/typevariable_substitution2_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.
 
 // Test that mixins don't interfere with type variable substitution.
 
 import 'checked_mode_helper.dart';
 
 class B<T> {
   B(T x);
 }
 
 class M {}
 
 class A<T> extends B<T> with M {
-  A(T x) : super(x);  // This line must be warning free.
+  A(T x) : super(x); // This line must be warning free.
 }
 
 class C<T> = B<T> with M;
 
-
 main() {
   new A(null);
   new C<String>(''); //# 01: ok
   checkDynamicTypeError(() => new C<String>(0)); //# 02: static type warning
 }