Revert

tests/language/vm/optimized_guarded_field_test.dart

-// Copyright (c) 2013, 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.
-// Test correct handling of phis with only environment uses that were inserted
-// by store to load forwarding.
-// VMOptions=--optimization_counter_threshold=10
-
-import "package:expect/expect.dart";
-
-class A {
-  var foo;
-}
-
-class B {
-  get foo => null;
-}
-
-test(obj) => obj.foo == null ? "null" : "other";
-
-main() {
-  var a = new A();
-  var b = new B();
-  // Trigger optimization of test with a polymorphic load.
-  // The guarded type of foo is null.
-  test(a);
-  test(b);
-  for (var i = 0; i < 20; ++i) test(a);
-  Expect.equals("null", test(a));
-  Expect.equals("null", test(b));
-
-  // Store a non-null object into foo to trigger deoptimization of test.
-  a.foo = 123;
-  Expect.equals("other", test(a));
-  Expect.equals("null", test(b));
-}