BREAKING CHANGE: Remove === and !== in the VM compiler

tests/language/compile_time_constant8_test.dart

 // Copyright (c) 2012, 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.
 
 import "package:expect/expect.dart";
 
 class A<T> {
   const A();
   toString() => "a";
 }
 
 const a = const A<int>();
 const b = const A<double>();
 
 const list1 = const<int> [1, 2];
 const list2 = const [1, 2];
 main() {
-  Expect.isFalse(a === b);
-  Expect.isFalse(list1 === list2);
+  Expect.isFalse(identical(a, b));
+  Expect.isFalse(identical(list1, list2));
 }