Fix memory leak in MacOS process handling.

runtime/bin/eventhandler_win.cc

 // Copyright (c) 2011, 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 <process.h>
 #include <winsock2.h>
 #include <ws2tcpip.h>
 #include <mswsock.h>
 
 #include "bin/builtin.h"
@@ skipping 465 matching lines @@
 
 
 int Handle::Write(const void* buffer, int num_bytes) {
   ScopedLock lock(this);
   if (SupportsOverlappedIO()) {
     if (pending_write_ != NULL) return 0;
     if (completion_port_ == INVALID_HANDLE_VALUE) return 0;
     if (num_bytes > 4096) num_bytes = 4096;
     pending_write_ = IOBuffer::AllocateWriteBuffer(num_bytes);
     pending_write_->Write(buffer, num_bytes);
-    IssueWrite();
+    if (!IssueWrite()) return -1;
     return num_bytes;
   } else {
-    DWORD bytes_written;
+    DWORD bytes_written = -1;
     BOOL ok = WriteFile(handle_,
                         buffer,
                         num_bytes,
                         &bytes_written,
                         NULL);
     if (!ok) {
       if (GetLastError() != ERROR_BROKEN_PIPE) {
         fprintf(stderr, "WriteFile failed: %d\n", GetLastError());
       }
       event_handler_->HandleClosed(this);
@@ skipping 382 matching lines @@
       _beginthreadex(NULL, 32 * 1024, EventHandlerThread, this, 0, &tid);
   if (thread_handle == -1) {
     FATAL("Failed to start event handler thread");
   }
 
   // Initialize Winsock32
   if (!Socket::Initialize()) {
     FATAL("Failed to initialized Windows sockets");
   }
 }