Move kernel baseline tests to front_end.

pkg/front_end/test/fasta/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;
-      ; // Empty statement.
-    }
-    case 2:
-    {
-      "Fall-through error needed.";
-      if (true) {
-        break;
-      }
-    }
-    case 3:
-      try {
-        "No fall-through error needed.";
-      } finally {
-        break;
-      }
-    case 4:
-      try {
-        "No fall-through error needed.";
-        break;
-      } finally {
-      }
-    case 5:
-      try {
-        "Fall-through error needed.";
-      } finally {
-      }
-    case 10000:
-      "Should be last. No fall-through error, falling through allowed here.";
-  }
-}