a === b -> identical(a, b)

tests/language/constant_fold_equals_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.
 
 main() {
   var a = 'foo';
   for (int i = 0; i < 10; i++) {
     if (i == 0) {
-      Expect.isTrue(a === 'foo');
+      Expect.isTrue(identical(a, 'foo'));
     } else {
-      Expect.isTrue(a === 2);
+      Expect.isTrue(a == 2);
     }
     a = 2;
   }
 }