Really remove io support when dart:io is unsupported.

runtime/bin/dartutils.cc

 // 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.
 
 #include "bin/dartutils.h"
 
-#include "include/dart_api.h"
-#include "include/dart_tools_api.h"
-#include "include/dart_native_api.h"
-
-#include "platform/assert.h"
-#include "platform/globals.h"
-
 #include "bin/crypto.h"
 #include "bin/directory.h"
 #include "bin/extensions.h"
 #include "bin/file.h"
 #include "bin/io_buffer.h"
 #include "bin/platform.h"
-#include "bin/socket.h"
 #include "bin/utils.h"
 
+#include "include/dart_api.h"
+#include "include/dart_native_api.h"
+#include "include/dart_tools_api.h"
+
+#include "platform/assert.h"
+#include "platform/globals.h"
+
 // Return the error from the containing function if handle is in error handle.
 #define RETURN_IF_ERROR(handle)                                                \
   {                                                                            \
     Dart_Handle __handle = handle;                                             \
     if (Dart_IsError((__handle))) {                                            \
       return __handle;                                                         \
     }                                                                          \
   }
 
 namespace dart {
@@ skipping 1227 matching lines @@
       new CObjectString(CObject::NewString(os_error->message()));
   CObjectArray* result = new CObjectArray(CObject::NewArray(3));
   result->SetAt(0, new CObjectInt32(CObject::NewInt32(kOSError)));
   result->SetAt(1, new CObjectInt32(CObject::NewInt32(os_error->code())));
   result->SetAt(2, error_message);
   return result;
 }
 
 }  // namespace bin
 }  // namespace dart