Implement a getter for pattern to complete the Match interface.

runtime/lib/regexp.dart

 // Copyright (c) 2011, 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 start() {
     return _start(0);
   }
@@ skipping 32 matching lines @@
     for (int i = 0; i < groupsSpec.length; i++) {
       groupsList[i] = group(groupsSpec[i]);
     }
     return groupsList;
   }
 
   int groupCount() {
     return regexp._groupCount;
   }
 
+  String get pattern() => regexp.pattern;
+
   final RegExp regexp;
   final String str;
   final List<int> _match;
   static final int MATCH_PAIR = 2;
 }
 
 
 class JSSyntaxRegExp implements RegExp {
   const factory JSSyntaxRegExp(
       String pattern,
@@ skipping 47 matching lines @@
 
   bool get multiLine() native "JSSyntaxRegExp_multiLine";
 
   bool get ignoreCase() native "JSSyntaxRegExp_ignoreCase";
 
   int get _groupCount() native "JSSyntaxRegExp_getGroupCount";
 
   List _ExecuteMatch(String str, int start_index)
       native "JSSyntaxRegExp_ExecuteMatch";
 }