Fix potential use-after-free bug in windows eventhandler

dart/runtime/bin/eventhandler_win.cc

 // Copyright (c) 2013, 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_WINDOWS)
 
 #include "bin/eventhandler.h"
 #include "bin/eventhandler_win.h"
 
@@ skipping 1011 matching lines @@
 
         // We only close the socket file descriptor from the operating
         // system if there are no other dart socket objects which
         // are listening on the same (address, port) combination.
         ListeningSocketRegistry *registry =
             ListeningSocketRegistry::Instance();
         MutexLocker locker(registry->mutex());
         if (registry->CloseSafe(reinterpret_cast<intptr_t>(listen_socket))) {
           ASSERT(listen_socket->Mask() == 0);
           listen_socket->Close();
-          DeleteIfClosed(handle);
         }
 
         DartUtils::PostInt32(msg->dart_port, 1 << kDestroyedEvent);
       } else {
         UNREACHABLE();
       }
     } else {
       handle->EnsureInitialized(this);
-
       Handle::ScopedLock lock(handle);
 
       if (IS_COMMAND(msg->data, kReturnTokenCommand)) {
         handle->ReturnTokens(msg->dart_port, TOKEN_COUNT(msg->data));
       } else if (IS_COMMAND(msg->data, kSetEventMaskCommand)) {
         // `events` can only have kInEvent/kOutEvent flags set.
         intptr_t events = msg->data & EVENT_MASK;
         ASSERT(0 == (events & ~(1 << kInEvent | 1 << kOutEvent)));
 
         handle->SetPortAndMask(msg->dart_port, events);
@@ skipping 42 matching lines @@
         ASSERT(handle->is_client_socket());
 
         ClientSocket* client_socket = reinterpret_cast<ClientSocket*>(handle);
         client_socket->Shutdown(SD_SEND);
       } else if (IS_COMMAND(msg->data, kCloseCommand)) {
         handle->SetPortAndMask(msg->dart_port, 0);
         handle->Close();
       } else {
         UNREACHABLE();
       }
-      DeleteIfClosed(handle);
     }
+
+    DeleteIfClosed(handle);
   }
 }
 
 
 void EventHandlerImplementation::HandleAccept(ListenSocket* listen_socket,
                                               OverlappedBuffer* buffer) {
   listen_socket->AcceptComplete(buffer, completion_port_);
 
   {
     Handle::ScopedLock lock(listen_socket);
@@ skipping 272 matching lines @@
 
 
 void EventHandlerImplementation::Shutdown() {
   SendData(kShutdownId, 0, 0);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)