Run formatter on a few frontend and kernel files that hadn't been formatted.

pkg/front_end/testcases/rasta/class_hierarchy.dart

 // Copyright (c) 2016, 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.
 
 class A extends Missing {}
+
 class B implements Missing {}
+
 class C = Object with Missing;
 
 class D {
   factory D() = Missing;
 }
 
 void main() {
   new A();
   new B();
   new C();
   new D();
 }