dart:io | Fix a crash when read was called on a closed socket on Windows.

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([String address = "127.0.0.1",
                                                    int port = 0,
                                                    int backlog = 0]) {
     return _RawServerSocket.bind(address, port, backlog);
   }
@@ skipping 134 matching lines @@
       return 0;
     } else {
       return result;
     }
   }
 
   List<int> read(int len) {
     if (len != null && len <= 0) {
       throw new ArgumentError("Illegal length $len");
     }
+    if (isClosed) return null;
     var result = nativeRead(len == null ? -1 : len);
     if (result is OSError) {
       reportError(result, "Read failed");
       return null;
     }
     return result;
   }
 
   int write(List<int> buffer, int offset, int bytes) {
     if (buffer is! List) throw new ArgumentError();
@@ skipping 756 matching lines @@
     _raw.onBadCertificate = callback;
   }
 
   X509Certificate get peerCertificate {
     if (_raw == null) {
      throw new StateError("peerCertificate called on destroyed SecureSocket");
     }
     return _raw.peerCertificate;
   }
 }