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

tests/language/const_nested_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.
 
 // Test of compile time constant local variables in outer function levels.
 
 const N = 8;
 
 class ConstFoo {
   final x;
   const ConstFoo(this.x);
 }
 
 getClosure() {
   const MIN = 2 - 1;
   const MAX = N * 2;
   const MASK = (1 << (MAX - MIN + 1)) - 1;  // 65535.
 
   void foo() {
     Expect.equals(1, MIN);
     Expect.equals(16, MAX);
     Expect.equals(65535, MASK);
     // Refer to compile time constant local variables in outer scope.
     const s = 'MIN = $MIN  MAX = $MAX  MASK = $MASK';
-    Expect.isTrue(s === 'MIN = $MIN  MAX = $MAX  MASK = $MASK');
+    Expect.isTrue(identical(s, 'MIN = $MIN  MAX = $MAX  MASK = $MASK'));
     Expect.equals("MIN = 1  MAX = 16  MASK = 65535", s);
     var cf1 = const ConstFoo(MASK);
     var cf2 = const ConstFoo(s);
     var cf3 = const ConstFoo('MIN = $MIN  MAX = $MAX  MASK = $MASK');
-    Expect.isTrue(cf2 === cf3);
-    Expect.isFalse(cf2 === cf1);
+    Expect.isTrue(identical(cf2, cf3));
+    Expect.isFalse(identical(cf2, cf1));
   }
 
   return foo;
 }
 
 
 main() {
   var f = getClosure();
   f();
 }