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

sdk/lib/io/stream_util.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.
 
 abstract class _BaseDataInputStream {
   int available();
 
   List<int> read([int len]) {
     if (_closeCallbackCalled || _scheduledCloseCallback != null) return null;
     int bytesToRead = available();
     if (bytesToRead == 0) {
       _checkScheduleCallbacks();
       return null;
     }
-    if (len !== null) {
+    if (len != null) {
       if (len <= 0) {
         throw new StreamException("Illegal length $len");
       } else if (bytesToRead > len) {
         bytesToRead = len;
       }
     }
     return _read(bytesToRead);
   }
 
   int readInto(List<int> buffer, [int offset = 0, int len]) {
     if (_closeCallbackCalled || _scheduledCloseCallback != null) return 0;
-    if (len === null) len = buffer.length;
+    if (len == null) len = buffer.length;
     if (offset < 0) throw new StreamException("Illegal offset $offset");
     if (len < 0) throw new StreamException("Illegal length $len");
     int bytesToRead = min(len, available());
     return _readInto(buffer, offset, bytesToRead);
   }
 
   void pipe(OutputStream output, {bool close: true}) {
     _pipe(this, output, close: close);
   }
 
@@ skipping 26 matching lines @@
       throw e;
     }
   }
 
   List<int> _read(int bytesToRead);
 
   void _dataReceived() {
     // More data has been received asynchronously. Perform the data
     // handler callback now.
     _cancelScheduledDataCallback();
-    if (_clientDataHandler !== null) {
+    if (_clientDataHandler != null) {
       _clientDataHandler();
     }
     _checkScheduleCallbacks();
   }
 
   void _closeReceived() {
     // Close indication has been received asynchronously. Perform the
     // close callback now if all data has been delivered.
     _streamMarkedClosed = true;
     if (available() == 0) {
       _closeCallbackCalled = true;
-      if (_clientCloseHandler !== null) _clientCloseHandler();
+      if (_clientCloseHandler != null) _clientCloseHandler();
     } else {
       _checkScheduleCallbacks();
     }
   }
 
   void _cancelScheduledDataCallback() {
     if (_scheduledDataCallback != null) {
       _scheduledDataCallback.cancel();
       _scheduledDataCallback = null;
     }
   }
 
   void _checkScheduleCallbacks() {
     void issueDataCallback(Timer timer) {
       _scheduledDataCallback = null;
-      if (_clientDataHandler !== null) {
+      if (_clientDataHandler != null) {
         _clientDataHandler();
         _checkScheduleCallbacks();
       }
     }
 
     void issueCloseCallback(Timer timer) {
       _scheduledCloseCallback = null;
       _closeCallbackCalled = true;
-      if (_clientCloseHandler !== null) _clientCloseHandler();
+      if (_clientCloseHandler != null) _clientCloseHandler();
     }
 
     // Schedule data callback if there is more data to read. Schedule
     // close callback once when all data has been read. Only schedule
     // a new callback if the previous one has actually been called.
     if (!_closeCallbackCalled) {
       if (available() > 0) {
         if (_scheduledDataCallback == null) {
           _scheduledDataCallback = new Timer(0, issueDataCallback);
         }
@@ skipping 25 matching lines @@
 
 void _pipe(InputStream input, OutputStream output, {bool close}) {
   Function pipeDataHandler;
   Function pipeCloseHandler;
   Function pipeNoPendingWriteHandler;
 
   Function _inputCloseHandler;
 
   pipeDataHandler = () {
     List<int> data;
-    while ((data = input.read()) !== null) {
+    while ((data = input.read()) != null) {
       if (!output.write(data)) {
         input.onData = null;
         output.onNoPendingWrites = pipeNoPendingWriteHandler;
         break;
       }
     }
   };
 
   pipeCloseHandler = () {
     if (close) output.close();
-    if (_inputCloseHandler !== null) {
+    if (_inputCloseHandler != null) {
       _inputCloseHandler();
     }
   };
 
   pipeNoPendingWriteHandler = () {
     input.onData = pipeDataHandler;
     output.onNoPendingWrites = null;
   };
 
   _inputCloseHandler = input._clientCloseHandler;
@@ skipping 21 matching lines @@
   void _reportError(e) {
     if (_onError != null) {
       _onError(e);
     } else {
       throw e;
     }
   }
 
   Function _onError;
 }