Fix upgrade to secure issue

tests/standalone/io/raw_secure_server_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 315 matching lines @@
             Expect.isTrue(data[i] is int);
             Expect.isTrue(data[i] < 256 && data[i] >= 0);
           }
           bytesWritten += client.write(
               data, bytesWritten, data.length - bytesWritten);
           if (bytesWritten < data.length) {
             client.writeEventsEnabled = true;
           }
           if (bytesWritten == data.length) {
             if (!postponeSecure) {
-              client.readEventsEnabled = true;
               completer.complete([subscription, null]);
             }
           }
           break;
         case RawSocketEvent.READ_CLOSED:
           Expect.fail("Unexpected close");
           break;
         default: throw "Unexpected event $event";
       }
     });
@@ skipping 103 matching lines @@
   testSimpleConnectFail("not_a_nickname");
   testSimpleConnectFail("CN=notARealDistinguishedName");
   testServerListenAfterConnect();
   testSimpleReadWrite(true, true, false);
   testSimpleReadWrite(true, false, false);
   testSimpleReadWrite(false, true, false);
   testSimpleReadWrite(false, false, false);
   testSimpleReadWrite(false, false, true, true);
   testSimpleReadWrite(false, false, true, false);
 }