Move kernel baseline tests to front_end.

pkg/front_end/testcases/rasta/issue_000026.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.
 
 class C {
   var a;
   var b = 0;
   var c = 1 + 2;
 }
 
 class D {
   var a;
   var b = 1;
   var c = 2 - 3;
   D();
 }
 
 main() {
   new C();
   new D();
 }