dart:io | Fix error in raw_server_socket_cancel_test.

tests/standalone/io/raw_server_socket_cancel_test.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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 import "dart:async";
 import "dart:io";
 import "dart:isolate";
 
 void testCancelResubscribeServerSocket(int socketCount, int backlog) {
   var acceptCount = 0;
   var doneCount = 0;
   var closeCount = 0;
   var errorCount = 0;
+  var earlyErrorCount = 0;
 
   ReceivePort port = new ReceivePort();
 
   RawServerSocket.bind("127.0.0.1", 0, backlog).then((server) {
     Expect.isTrue(server.port > 0);
 
     void checkDone() {
-      if (doneCount == socketCount &&
-          closeCount + errorCount == socketCount) {
+      if (doneCount + earlyErrorCount == socketCount &&
+          closeCount + errorCount + earlyErrorCount == socketCount) {
         port.close();
       }
     }
 
     var subscription;
     subscription = server.listen((client) {
       client.writeEventsEnabled = false;
       client.listen((event) {
         switch(event) {
           case RawSocketEvent.READ:
@@ skipping 45 matching lines @@
           doneCount++;
           checkDone();
         },
         onError: (e) {
           // "Connection reset by peer" errors are handled here.
           errorCount++;
           checkDone();
         });
       }).catchError((e) {
         // "Connection actively refused by host" errors are handled here.
-        errorCount++;
+        earlyErrorCount++;
         checkDone();
       });
     }
   });
 }
 
 void main() {
   testCancelResubscribeServerSocket(10, 20);
   testCancelResubscribeServerSocket(20, 5);
 }