Move kernel baseline tests to front_end.

pkg/front_end/testcases/literals.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.
 
 testString() {
   print("a");
 }
 
 testInt() {
   print(1);
@@ skipping 31 matching lines @@
 main() {
   testString();
   testInt();
   testBool();
   testDouble();
   testNull();
   testList();
   testMap();
   testSymbol();
 }