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

sdk/lib/_internal/compiler/implementation/lib/regexp_helper.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.
 
 List regExpExec(JSSyntaxRegExp regExp, String str) {
   var nativeRegExp = regExpGetNative(regExp);
   var result = JS('List', r'#.exec(#)', nativeRegExp, str);
-  if (JS('bool', r'# === null', result)) return null;
+  if (JS('bool', r'# == null', result)) return null;
   return result;
 }
 
 bool regExpTest(JSSyntaxRegExp regExp, String str) {
   var nativeRegExp = regExpGetNative(regExp);
   return JS('bool', r'#.test(#)', nativeRegExp, str);
 }
 
 regExpGetNative(JSSyntaxRegExp regExp) {
   var r = JS('var', r'#._re', regExp);
@@ skipping 18 matching lines @@
   if (global) sb.add('g');
   try {
     return JS('Object', r'new RegExp(#, #)', pattern, sb.toString());
   } catch (e) {
     throw new IllegalJSRegExpException(pattern,
                                        JS('String', r'String(#)', e));
   }
 }
 
 int regExpMatchStart(m) => JS('int', r'#.index', m);