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

sdk/lib/io/list_stream_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.
 
 /**
  * Default implementation of [ListInputStream].
  */
 class _ListInputStream extends _BaseDataInputStream implements ListInputStream {
   _ListInputStream() : _bufferList = new _BufferList();
 
@@ skipping 98 matching lines @@
       _scheduledNoPendingWriteCallback = null;
       if (_clientNoPendingWriteHandler != null &&
           !_streamMarkedClosed) {
         _clientNoPendingWriteHandler();
         _checkScheduleCallbacks();
       }
     }
 
     void issueCloseCallback(Timer timer) {
       _scheduledCloseCallback = null;
-      if (_clientCloseHandler !== null) _clientCloseHandler();
+      if (_clientCloseHandler != null) _clientCloseHandler();
     }
 
     // Schedule no pending callback if there is a callback set as this
     // output stream does not wait for any transmission. Schedule
     // close callback once when the stream is closed. Only schedule a
     // new callback if the previous one has actually been called.
     if (_closeCallbackCalled) return;
 
     if (!_streamMarkedClosed) {
       if (!_bufferList.isEmpty &&
@@ skipping 20 matching lines @@
   _BufferList _bufferList;
   bool _streamMarkedClosed = false;
   bool _closeCallbackCalled = false;
   Timer _scheduledDataCallback;
   Timer _scheduledNoPendingWriteCallback;
   Timer _scheduledCloseCallback;
   Function _clientDataHandler;
   Function _clientNoPendingWriteHandler;
   Function _clientCloseHandler;
 }