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

runtime/lib/growable_array.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 _GrowableObjectArray<T> implements List<T> {
   factory _GrowableObjectArray._uninstantiable() {
     throw new UnsupportedError(
         "GrowableObjectArray can only be allocated by the VM");
   }
 
@@ skipping 136 matching lines @@
 
   T get last {
     return this[length - 1];
   }
 
   int indexOf(T element, [int start = 0]) {
     return Arrays.indexOf(this, element, start, length);
   }
 
   int lastIndexOf(T element, [int start = null]) {
-    if (start === null) start = length - 1;
+    if (start == null) start = length - 1;
     return Arrays.lastIndexOf(this, element, start);
   }
 
   void _grow(int new_length) {
     var new_data = new _ObjectArray<T>(new_length);
     for (int i = 0; i < length; i++) {
       new_data[i] = this[i];
     }
     _setData(new_data);
   }
@@ skipping 25 matching lines @@
 
   bool every(bool f(T element)) {
     return Collections.every(this, f);
   }
 
   bool some(bool f(T element)) {
     return Collections.some(this, f);
   }
 
   bool get isEmpty {
-    return this.length === 0;
+    return this.length == 0;
   }
 
   void clear() {
     this.length = 0;
   }
 
   void sort([Comparator<T> compare = Comparable.compare]) {
     coreSort(this, compare);
   }
 
   String toString() {
     return Collections.collectionToString(this);
   }
 
   Iterator<T> iterator() {
     return new SequenceIterator<T>(this);
   }
 }