[dart:io] Remove DART_IO_DISABLED

runtime/bin/secure_socket_utils.cc

 // Copyright (c) 2017, 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.
 
-#if !defined(DART_IO_DISABLED) && !defined(DART_IO_SECURE_SOCKET_DISABLED)
+#if !defined(DART_IO_SECURE_SOCKET_DISABLED)
 
 #include "bin/secure_socket_utils.h"
 
 #include <openssl/err.h>
 #include <openssl/ssl.h>
 
 #include "platform/globals.h"
 
 #include "bin/file.h"
 #include "bin/log.h"
@@ skipping 69 matching lines @@
 
 void SecureSocketUtils::CheckStatus(int status,
                                     const char* type,
                                     const char* message) {
   SecureSocketUtils::CheckStatusSSL(status, type, message, NULL);
 }
 
 }  // namespace bin
 }  // namespace dart
 
-#endif  // !defined(DART_IO_DISABLED) &&
-        // !defined(DART_IO_SECURE_SOCKET_DISABLED)
+#endif  // !defined(DART_IO_SECURE_SOCKET_DISABLED)