Use ExitProcess on Windows.

runtime/bin/platform_linux.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 "platform/globals.h"
 #if defined(TARGET_OS_LINUX)
 
 #include "bin/file.h"
 #include "bin/platform.h"
 
@@ skipping 59 matching lines @@
 
 void Platform::FreeEnvironment(char** env, intptr_t count) {
   delete[] env;
 }
 
 
 char* Platform::ResolveExecutablePath() {
   return File::LinkTarget("/proc/self/exe");
 }
 
+void Platform::Exit(int exit_code) {
+  exit(exit_code);
+}
+
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_LINUX)