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

runtime/lib/regexp_patch.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 _JSRegExpMatch implements Match {
   _JSRegExpMatch(this.regexp, this.str, this._match);
 
   int get start => _start(0);
   int get end => _end(0);
 
@@ skipping 43 matching lines @@
 
 
 patch class JSSyntaxRegExp {
   /* patch */ const factory JSSyntaxRegExp(
       String pattern,
       {bool multiLine: false,
        bool ignoreCase: false}) native "JSSyntaxRegExp_factory";
 
   /* patch */ Match firstMatch(String str) {
     List match = _ExecuteMatch(str, 0);
-    if (match === null) {
+    if (match == null) {
       return null;
     }
     return new _JSRegExpMatch(this, str, match);
   }
 
   /* patch */ Iterable<Match> allMatches(String str) {
     List<Match> result = new List<Match>();
     int length = str.length;
     int startIndex = 0;
     while (true) {
       List match = _ExecuteMatch(str, startIndex);
       if (match == null) {
         break;
       }
       result.add(new _JSRegExpMatch(this, str, match));
       int endIndex = match[1];
       if (endIndex == length) {
         break;
       } else if (match[0] == endIndex) {
         ++startIndex;  // empty match, advance and restart
       } else {
         startIndex = endIndex;
       }
     }
     return result;
   }
 
   /* patch */ bool hasMatch(String str) {
     List match = _ExecuteMatch(str, 0);
-    return (match === null) ? false : true;
+    return (match == null) ? false : true;
   }
 
   /* patch */ String stringMatch(String str) {
     List match = _ExecuteMatch(str, 0);
-    if (match === null) {
+    if (match == null) {
       return null;
     }
     // TODO(ajohnsen): Use _substringUnchecked when regexp is in core.
     return str.substring(match[0], match[1]);
   }
 
   /* patch */ String get pattern native "JSSyntaxRegExp_getPattern";
 
   /* patch */ bool get multiLine native "JSSyntaxRegExp_multiLine";
 
   /* patch */ bool get ignoreCase native "JSSyntaxRegExp_ignoreCase";
 
   int get _groupCount native "JSSyntaxRegExp_getGroupCount";
 
   List _ExecuteMatch(String str, int start_index)
       native "JSSyntaxRegExp_ExecuteMatch";
 }