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

tests/compiler/dart2js/metadata_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.
 
 import "dart:uri";
 
 import 'compiler_helper.dart';
 import 'parser_helper.dart';
 
 import '../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart';
@@ skipping 26 matching lines @@
               $declaration
               main() {}""";
 
   compileAndCheck(source, name, (compiler, element) {
     compiler.enqueuer.resolution.queueIsClosed = false;
     Expect.equals(2, length(element.metadata));
     MetadataAnnotation annotation1 = element.metadata.head;
     MetadataAnnotation annotation2 = element.metadata.tail.head;
     annotation1.ensureResolved(compiler);
     annotation2.ensureResolved(compiler);
-    Expect.isTrue(annotation1 !== annotation2, 'expected unique instances');
+    Expect.isFalse(identical(annotation1, annotation2),
+                   'expected unique instances');
     Expect.notEquals(annotation1, annotation2, 'expected unequal instances');
     Constant value1 = annotation1.value;
     Constant value2 = annotation2.value;
     Expect.identical(value1, value2, 'expected same compile-time constant');
     Expect.stringEquals('xyz', value1.value.slowToString());
     Expect.stringEquals('xyz', value2.value.slowToString());
   });
 
   if (isTopLevelOnly) return;
 
@@ skipping 32 matching lines @@
     compiler.enqueuer.resolution.queueIsClosed = false;
     Expect.equals(0, length(element.metadata));
     element.ensureResolved(compiler);
     Expect.equals(0, length(element.metadata));
     element = element.lookupLocalMember(buildSourceString(name));
     Expect.equals(2, length(element.metadata));
     MetadataAnnotation annotation1 = element.metadata.head;
     MetadataAnnotation annotation2 = element.metadata.tail.head;
     annotation1.ensureResolved(compiler);
     annotation2.ensureResolved(compiler);
-    Expect.isTrue(annotation1 !== annotation2, 'expected unique instances');
+    Expect.isFalse(identical(annotation1, annotation2),
+                   'expected unique instances');
     Expect.notEquals(annotation1, annotation2, 'expected unequal instances');
     Constant value1 = annotation1.value;
     Constant value2 = annotation2.value;
     Expect.identical(value1, value2, 'expected same compile-time constant');
     Expect.stringEquals('xyz', value1.value.slowToString());
     Expect.stringEquals('xyz', value2.value.slowToString());
   });
 }
 
 void testClassMetadata() {
   checkAnnotation('Foo', 'class Foo {}', isTopLevelOnly: true);
 }
 
 void testTopLevelMethodMetadata() {
   checkAnnotation('foo', 'foo() {}');
 }
 
 void testTopLevelFieldMetadata() {
   checkAnnotation('foo', 'var foo;');
 }
 
 void main() {
   testClassMetadata();
   testTopLevelMethodMetadata();
   testTopLevelFieldMetadata();
 }