Move kernel baseline tests to front_end.

pkg/front_end/test/fasta/classes.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 {
-  final int x;
-  final int y;
-  A(this.y) : x = 42;
-  method() {
-    print("A.method x: $x y: $y");
-    print(this);
-    print(this.runtimeType);
-  }
-}
-
-class B extends A {
-  B(x) : super(x);
-  method() {
-    print("B.method x: $x y: $y");
-    super.method();
-  }
-}
-
-main() {
-  A a = new A(87);
-  B b = new B(117);
-  a.method();
-  b.method();
-}