Initializing formals can't be optional parameters

samples/chat/chat_server_lib.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.
 
 #library("chat_server");
 #import("http.dart");
 #import("../../client/json/dart_json.dart");
 
 typedef void RequestHandler(HTTPRequest request, HTTPResponse response);
 
 class ChatServer extends IsolatedServer {
   ChatServer() : super() {
     addHandler("/",
-               (HTTPRequest request, HTTPResponse response) 
+               (HTTPRequest request, HTTPResponse response)
                => redirectPageHandler(request, response, "dart_client/index.html"));
     addHandler("/js_client/index.html",
                (HTTPRequest request, HTTPResponse response) => fileHandler(request, response));
     addHandler("/js_client/code.js",
                (HTTPRequest request, HTTPResponse response) => fileHandler(request, response));
     addHandler("/dart_client/index.html",
                (HTTPRequest request, HTTPResponse response) => fileHandler(request, response));
     addHandler("/out/dart_client/chat.dart.app.js",
                (HTTPRequest request, HTTPResponse response) => fileHandler(request, response));
     addHandler("/favicon.ico",
@@ skipping 624 matching lines @@
 
 // Calculate the rate of events over a given time range. The time
 // range is split over a number of buckets where each bucket collects
 // the number of events happening in that time sub-range. The first
 // constructor arument specifies the time range in milliseconds. The
 // buckets are in the list _buckets organized at a circular buffer
 // with _currentBucket marking the bucket where an event was last
 // recorded. A current sum of the content of all buckets except the
 // one pointed a by _currentBucket is kept in _sum.
 class Rate {
-  Rate([int this._timeRange = 1000, int buckets = 10])
-      : _buckets = new List(buckets + 1),  // Current bucket is not in the sum.
+  Rate([int timeRange = 1000, int buckets = 10])
+      : _timeRange = timeRange,
+        _buckets = new List(buckets + 1),  // Current bucket is not in the sum.
         _currentBucket = 0,
         _currentBucketTime = new Date.now().value,
         _sum = 0 {
     _bucketTimeRange = (_timeRange / buckets).toInt();
     for (int i = 0; i < _buckets.length; i++) {
       _buckets[i] = 0;
     }
   }
 
   // Record the specified number of events.
@@ skipping 32 matching lines @@
     }
   }
 
   int _timeRange;
   List<int> _buckets;
   int _currentBucket;
   int _currentBucketTime;
   num _bucketTimeRange;
   int _sum;
 }