Fix raw_socket_test off-by-one issue.

tests/standalone/io/raw_socket_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 "package:expect/expect.dart";
@@ skipping 223 matching lines @@
         server.close();
         port.close();
       }
     });
 
     // Pause the server socket subscription and resume it after having
     // connected a number client sockets. Then connect more client
     // sockets.
     subscription.pause();
     var connectCount = 0;
-    for (int i = 0; i <= socketCount / 2; i++) {
+    for (int i = 0; i < socketCount / 2; i++) {
       RawSocket.connect("127.0.0.1", server.port).then((_) {
         if (++connectCount == socketCount / 2) {
           subscription.resume();
           resumed = true;
           for (int i = connectCount; i < socketCount; i++) {
             RawSocket.connect("127.0.0.1", server.port).then((_) {});
           }
         }
       });
     }
@@ skipping 85 matching lines @@
   testSimpleBind();
   testCloseOneEnd("client");
   testCloseOneEnd("server");
   testInvalidBind();
   testSimpleConnect();
   testServerListenAfterConnect();
   testSimpleReadWrite();
   testPauseServerSocket();
   testPauseSocket();
 }