Don't try to call read, if len i 0.

runtime/bin/socket_patch.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.
 
 patch class RawServerSocket {
   /* patch */ static Future<RawServerSocket> bind(address,
                                                   int port,
                                                   {int backlog: 0,
                                                    bool v6Only: false}) {
     return _RawServerSocket.bind(address, port, backlog, v6Only);
@@ skipping 431 matching lines @@
   _NativeSocket.watch(int id) : typeFlags = TYPE_NORMAL_SOCKET {
     isClosedWrite = true;
     nativeSetSocketId(id);
   }
 
   List<int> read(int len) {
     if (len != null && len <= 0) {
       throw new ArgumentError("Illegal length $len");
     }
     if (isClosing || isClosed) return null;
-    var result = nativeRead(min(available, len == null ? available : len));
+    len = min(available, len == null ? available : len);
+    if (len == 0) return null;
+    var result = nativeRead(len);
     if (result is OSError) {
       reportError(result, "Read failed");
       return null;
     }
     if (result != null) available -= result.length;
     return result;
   }
 
   Datagram receive() {
     if (isClosing || isClosed) return null;
@@ skipping 1124 matching lines @@
 
 Datagram _makeDatagram(List<int> data,
                        String address,
                        List<int> in_addr,
                        int port) {
   return new Datagram(
       data,
       new _InternetAddress(address, null, in_addr),
       port);
 }