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

tests/compiler/dart2js_extra/bailout_on_break_test.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 A {
   operator+(arg) => 42;
 }
 
 get42() => 42;
 getNonInt() => new A();
 use(x) => x;
 
 void testInWhileLoop() {
   var c = get42();
   while (true) {
     var e = getNonInt();
     Expect.equals(42, e + 2);
-    if (e !== null) break;
+    if (e != null) break;
     while (true) use(e);
   }
   // This is what matters: 'c' must have been saved in the
   // environment.
   Expect.equals(c, 42);
 }
 
 void testInNestedWhileLoop() {
   var c = get42();
   while (true) {
     while (true) {
       var e = getNonInt();
       Expect.equals(42, e + 2);
-      if (e !== null) break;
+      if (e != null) break;
     }
     // This is what matters: 'c' must have been saved in the
     // environment.
     Expect.equals(c, 42);
     if (c == 42) break;
   }
 }
 
 void testInNestedWhileLoop2() {
   var c = get42();
   L0: while (true) {
     while (true) {
       var e = getNonInt();
       Expect.equals(42, e + 2);
-      if (e !== null) break L0;
+      if (e != null) break L0;
       while (true) use(e);
     }
   }
   // This is what matters: 'c' must have been saved in the
   // environment.
   Expect.equals(c, 42);
 }
 
 void testInNestedWhileLoop3() {
   var c = get42();
   int index = 0;
   while (index < 2) {
     while (index < 2) {
       var e = getNonInt();
       Expect.equals(42, e + 2);
-      if (e !== null && index++ == 0) break;
+      if (e != null && index++ == 0) break;
       // This is what matters: 'c' must have been saved in the
       // environment.
       Expect.equals(c, 42);
-      while (e === null) use(e);
+      while (e == null) use(e);
     }
   }
 }
 
 void testInDoWhileLoop() {
   var c = get42();
   do {
     var e = getNonInt();
     Expect.equals(42, e + 2);
-    if (e !== null) break;
+    if (e != null) break;
     while (true) use(e);
   } while (true);
   // This is what matters: 'c' must have been saved in the
   // environment.
   Expect.equals(c, 42);
 }
 
 void testInForLoop() {
   var c = get42();
   for (int i = 0; i < 10; i++) {
     var e = getNonInt();
     Expect.equals(42, e + 2);
-    if (e !== null) break;
+    if (e != null) break;
     while (true) use(e);
   }
   // This is what matters: 'c' must have been saved in the
   // environment.
   Expect.equals(c, 42);
 }
 
 void testLabeledIf() {
   var c = get42();
   L1: if (c == 42) {
     var e = getNonInt();
     Expect.equals(42, e + 2);
-    if (e === null) break L1;
+    if (e == null) break L1;
     // This is what matters: 'c' must have been saved in the
     // environment.
     Expect.equals(c, 42);
-    while (e === null) use(e);
+    while (e == null) use(e);
   }
   Expect.equals(c, 42);
 }
 
 void testLabeledIf2() {
   var c = get42();
   L1: if (c == 42) {
     var e = getNonInt();
     Expect.equals(42, e + 2);
-    if (e === null) break L1;
+    if (e == null) break L1;
     Expect.equals(42, e + 1);
-    while (e === null) use(e);
+    while (e == null) use(e);
   }
   Expect.equals(42, c);
 }
 
 main() {
   testInWhileLoop();
   testInDoWhileLoop();
   testInForLoop();
   testInNestedWhileLoop();
   testInNestedWhileLoop2();
   testInNestedWhileLoop3();
   testLabeledIf();
   testLabeledIf2();
 }