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

sdk/lib/io/timer_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 _Timer implements Timer {
   // Set jitter to wake up timer events that would happen in _TIMER_JITTER ms.
   static const int _TIMER_JITTER = 0;
 
   // Disables the timer.
   static const int _NO_TIMER = -1;
 
   static Timer _createTimer(void callback(Timer timer),
                            int milliSeconds,
                            bool repeating) {
     _EventHandler._start();
-    if (_timers === null) {
+    if (_timers == null) {
       _timers = new DoubleLinkedQueue<_Timer>();
     }
     Timer timer = new _Timer._internal();
     timer._callback = callback;
     timer._milliSeconds = milliSeconds;
     timer._wakeupTime = (new Date.now()).millisecondsSinceEpoch + milliSeconds;
     timer._repeating = repeating;
     timer._addTimerToList();
     timer._notifyEventHandler();
     return timer;
@@ skipping 17 matching lines @@
   }
 
 
   // Cancels a set timer. The timer is removed from the timer list and if
   // the given timer is the earliest timer the native timer is reset.
   void cancel() {
     _clear();
     DoubleLinkedQueueEntry<_Timer> entry = _timers.firstEntry();
     DoubleLinkedQueueEntry<_Timer> first = _timers.firstEntry();
 
-     while (entry !== null) {
-      if (entry.element === this) {
+     while (entry != null) {
+      if (identical(entry.element, this)) {
         entry.remove();
         if (first.element == this) {
           entry = _timers.firstEntry();
           _notifyEventHandler();
         }
         return;
       }
       entry = entry.nextEntry();
     }
   }
 
   void _advanceWakeupTime() {
     _wakeupTime += _milliSeconds;
   }
 
   // Adds a timer to the timer list and resets the native timer if it is the
   // earliest timer in the list.  Timers with the same wakeup time are enqueued
   // in order and notified in FIFO order.
   void _addTimerToList() {
-    if (_callback !== null) {
+    if (_callback != null) {
 
       DoubleLinkedQueueEntry<_Timer> entry = _timers.firstEntry();
-      while (entry !== null) {
+      while (entry != null) {
         if (_wakeupTime < entry.element._wakeupTime) {
           entry.prepend(this);
           return;
         }
         entry = entry.nextEntry();
       }
       _timers.addLast(this);
     }
   }
 
 
   void _notifyEventHandler() {
     if (_handling_callbacks) {
       // While we are already handling callbacks we will not notify the event
       // handler. _handleTimeout will call _notifyEventHandler once all pending
       // timers are processed.
       return;
     }
 
-    if (_timers.firstEntry() === null) {
+    if (_timers.firstEntry() == null) {
       // No pending timers: Close the receive port and let the event handler
       // know.
-      if (_receivePort !== null) {
+      if (_receivePort != null) {
         _EventHandler._sendData(null, _receivePort, _NO_TIMER);
         _shutdownTimerHandler();
       }
     } else {
-      if (_receivePort === null) {
+      if (_receivePort == null) {
         // Create a receive port and register a message handler for the timer
         // events.
         _createTimerHandler();
       }
       _EventHandler._sendData(null,
                               _receivePort,
                               _timers.firstEntry().element._wakeupTime);
     }
   }
 
 
   // Creates a receive port and registers the timer handler on that
   // receive port.
   void _createTimerHandler() {
 
     void _handleTimeout() {
       int currentTime =
           (new Date.now()).millisecondsSinceEpoch + _TIMER_JITTER;
 
       // Collect all pending timers.
       DoubleLinkedQueueEntry<_Timer> entry = _timers.firstEntry();
       var pending_timers = new List();
-      while (entry !== null) {
+      while (entry != null) {
         _Timer timer = entry.element;
         if (timer._wakeupTime <= currentTime) {
           entry.remove();
           pending_timers.addLast(timer);
           entry = _timers.firstEntry();
         } else {
           break;
         }
       }
 
@@ skipping 13 matching lines @@
               timer._addTimerToList();
             }
           }
         }
       } finally {
         _handling_callbacks = false;
       }
       _notifyEventHandler();
     }
 
-    if(_receivePort === null) {
+    if(_receivePort == null) {
       _receivePort = new ReceivePort();
       _receivePort.receive((var message, ignored) {
         _handleTimeout();
       });
     }
   }
 
   void _shutdownTimerHandler() {
     _receivePort.close();
     _receivePort = null;
@@ skipping 17 matching lines @@
 _getTimerFactoryClosure() {
   return (int milliSeconds, void callback(Timer timer), bool repeating) {
     if (repeating) {
       return new _Timer.repeating(milliSeconds, callback);
     }
     return new _Timer(milliSeconds, callback);
   };
 }