Move kernel baseline tests to front_end.

pkg/front_end/test/fasta/operators.dart

-// Copyright (c) 2017, 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 Operators {
-  operator +(other) => null;
-  operator &(other) => null;
-  operator ~() => null;
-  operator |(other) => null;
-  operator ^(other) => null;
-  operator /(other) => null;
-  operator ==(other) => null;
-  operator >(other) => null;
-  operator >=(other) => null;
-  operator [](index) => null;
-  void operator []=(index, value) {}
-  operator <<(other) => null;
-  operator <(other) => null;
-  operator <=(other) => null;
-  operator *(other) => null;
-  operator %(other) => null;
-  operator >>(other) => null;
-  operator -(other) => null;
-  operator ~/(other) => null;
-  operator -() => null;
-}
-
-main(arguments) {
-  var a = new Operators();
-  var b = new Operators();
-  a + b;
-  a & b;
-  ~a;
-  a | b;
-  a ^ b;
-  a / b;
-  a == b;
-  a > b;
-  a >= b;
-  a[0];
-  a[0] = b;
-  a << b;
-  a < b;
-  a <= b;
-  a * b;
-  a % b;
-  a >> b;
-  a - b;
-  a ~/ b;
-  -a;
-}