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

tests/language/scope_variable_test.dart

 // Copyright (c) 2011, 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 ScopeVariableTest {
 
   static void testSimpleScope() {
     {
       var a = "Test";
       int b = 1;
     }
     {
       var c;
       int d;
-      Expect.equals(true, c === null);
-      Expect.equals(true, d === null);
+      Expect.equals(true, c == null);
+      Expect.equals(true, d == null);
     }
   }
 
   static void testShadowingScope() {
     var a = "Test";
     {
       var a;
-      Expect.equals(true, a === null);
+      Expect.equals(true, a == null);
       a = "a";
       Expect.equals(true, a == "a");
     }
     Expect.equals(true, a == "Test");
   }
 
   static void testMain() {
     testSimpleScope();
     testShadowingScope();
   }
 }
 
 main() {
   ScopeVariableTest.testMain();
 }