pkg/isolate: spelling fixes

lib/load_balancer.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.
 
 /// A load-balancing runner pool.
 library isolate.load_balancer;
 
 import 'dart:async' show Future;
 
 import 'runner.dart';
@@ skipping 249 matching lines @@
   int queueIndex = -1;
 
   // The service used to send commands to the other isolate.
   Runner runner;
 
   _LoadBalancerEntry(Runner runner) : runner = runner;
 
   /// Whether the entry is still in the queue.
   bool get inQueue => queueIndex >= 0;
 
-  Future run(LoadBalancer balancer, int load, function(argumen), argument,
+  Future run(LoadBalancer balancer, int load, function(argument), argument,
              Duration timeout, onTimeout()) {
     return runner.run(function, argument,
                       timeout: timeout, onTimeout: onTimeout).whenComplete(() {
       balancer._decreaseLoad(this, load);
     });
   }
 
   Future close() => runner.close();
 
   int compareTo(_LoadBalancerEntry other) => load - other.load;
 }