Increment next sequence number

runtime/lib/developer.dart

 // Copyright (c) 2015, 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.
 
 patch bool debugger({bool when: true,
                      String message}) native "Developer_debugger";
 
 patch Object inspect(Object object) native "Developer_inspect";
 
 patch log(String message,
           {DateTime time,
            int sequenceNumber,
            int level: 0,
            String name: '',
            Zone zone,
            Object error,
            StackTrace stackTrace}) {
   if (message is! String) {
     throw new ArgumentError(message, "message", "Must be a String");
   }
   if (time == null) {
     time = new DateTime.now();
   }
   if (time is! DateTime) {
     throw new ArgumentError(time, "time", "Must be a DateTime");
   }
   if (sequenceNumber == null) {
-    sequenceNumber = _nextSequenceNumber;
+    sequenceNumber = _nextSequenceNumber++;
   } else {
     _nextSequenceNumber = sequenceNumber + 1;
   }
   return _log(message,
               time.millisecondsSinceEpoch,
               sequenceNumber,
               level,
               name,
               zone,
               error,
               stackTrace);
 }
 
 int _nextSequenceNumber = 0;
 
 _log(String message,
      int timestamp,
      int sequenceNumber,
      int level,
      String name,
      Zone zone,
      Object error,
      StackTrace stackTrace) native "Developer_log";