Added Socket::Close() function.

runtime/bin/socket_macos.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 <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ skipping 232 matching lines @@
       // error. We got woken up from the poll on the listening socket,
       // but there is no connection ready to be accepted.
       ASSERT(kTemporaryFailure != -1);
       socket = kTemporaryFailure;
     }
   } else {
     FDUtils::SetNonBlocking(socket);
   }
   return socket;
 }
+
+
+void Socket::Close(intptr_t fd) {
+  ASSERT(fd >= 0);
+  int err = TEMP_FAILURE_RETRY(close(fd));
+  if (err != 0) {
+    const int kBufferSize = 1024;
+    char error_message[kBufferSize];
+    strerror_r(errno, error_message, kBufferSize);
+    Log::PrintErr("%s\n", error_message);
+  }
+}