Move kernel baseline tests to front_end.

pkg/front_end/testcases/rasta/switch_fall_through.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.md file.
 
 main() {
   switch (1) {
     case 1:
     {
       "No fall-through error needed.";
       break;
@@ skipping 20 matching lines @@
       }
     case 5:
       try {
         "Fall-through error needed.";
       } finally {
       }
     case 10000:
       "Should be last. No fall-through error, falling through allowed here.";
   }
 }