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

sdk/lib/io/http_impl.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.
 
 class _HttpHeaders implements HttpHeaders {
   _HttpHeaders() : _headers = new Map<String, List<String>>();
 
   List<String> operator[](String name) {
     name = name.toLowerCase();
     return _headers[name];
@@ skipping 1529 matching lines @@
       _server.close();
     }
     _server = null;
     for (_HttpConnection connection in _connections) {
       connection._destroy();
     }
     _connections.clear();
   }
 
   int get port {
-    if (_server === null) {
+    if (_server == null) {
       throw new HttpException("The HttpServer is not listening on a port.");
     }
     return _server.port;
   }
 
   void set onError(void callback(e)) {
     _onError = callback;
   }
 
   set sessionTimeout(int timeout) {
@@ skipping 1094 matching lines @@
 
 
 class _RedirectInfo implements RedirectInfo {
   const _RedirectInfo(int this.statusCode,
                       String this.method,
                       Uri this.location);
   final int statusCode;
   final String method;
   final Uri location;
 }