Add optional start index to Pattern.allMatches.

third_party/pkg/route_hierarchical/lib/pattern.dart

 // Copyright (c) 2013, 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.
 
 /**
  * Pattern utilities for use with server.Router.
  *
  * Example:
  *
  *     var router = new Router(server);
@@ skipping 60 matching lines @@
 
 /// return the tail
 Match prefixMatch(Pattern pattern, String str) {
   Iterable<Match> matches = pattern.allMatches(str);
   if (!matches.isEmpty && matches.first.start == 0) {
     return matches.first;
   }
   return null;
 }
 
-bool _hasMatch(Iterable<Match> matches) => matches.iterator.moveNext();
+bool _hasMatch(Iterable<Match> matches) => matches.iterator.moveNext();