Revert r43217, r43215, r43208, r43207, and r43202.

runtime/bin/secure_socket.h

 // Copyright (c) 2012, 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.
 
 #ifndef BIN_SECURE_SOCKET_H_
 #define BIN_SECURE_SOCKET_H_
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #include <sys/types.h>
 
-#if !defined(DART_IO_SECURE_SOCKET_DISABLED)
 #include <prinit.h>
 #include <prerror.h>
 #include <prnetdb.h>
 #include <ssl.h>
-#else
-struct PRFileDesc;
-#endif
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 #include "bin/socket.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
 
 namespace dart {
 namespace bin {
 
@@ skipping 89 matching lines @@
   void InitializeBuffers(Dart_Handle dart_this);
   void InitializePlatformData();
 
   DISALLOW_COPY_AND_ASSIGN(SSLFilter);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_SECURE_SOCKET_H_