Revert "[d8] cleanly force exit in d8 on windows."

src/d8-posix.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/select.h>
@@ skipping 754 matching lines @@
                     .ToLocalChecked(),
                 FunctionTemplate::New(isolate, SetUMask));
   os_templ->Set(String::NewFromUtf8(isolate, "mkdirp", NewStringType::kNormal)
                     .ToLocalChecked(),
                 FunctionTemplate::New(isolate, MakeDirectory));
   os_templ->Set(String::NewFromUtf8(isolate, "rmdir", NewStringType::kNormal)
                     .ToLocalChecked(),
                 FunctionTemplate::New(isolate, RemoveDirectory));
 }
 
-void Shell::Exit(int exit_code) {
-  // Use _exit instead of exit to avoid races between isolate
-  // threads and static destructors.
-  fflush(stdout);
-  fflush(stderr);
-  _exit(exit_code);
-}
-
 }  // namespace v8