Make std* blocking file-descriptors.

runtime/bin/eventhandler_macos.cc

Index: runtime/bin/eventhandler_macos.cc
diff --git a/runtime/bin/eventhandler_macos.cc b/runtime/bin/eventhandler_macos.cc
index bf047a485071ab41044a3c8127e2a49b26f5c4e5..c090e3a4bb7348a29294525652948be8d8f00f85 100644
--- a/runtime/bin/eventhandler_macos.cc
+++ b/runtime/bin/eventhandler_macos.cc
@@ -239,15 +239,7 @@ void EventHandlerImplementation::HandleInterruptFd() {
         // Close the socket and free system resources.
         RemoveFromKqueue(kqueue_fd_, sd);
         intptr_t fd = sd->fd();
-        if (fd == STDOUT_FILENO) {
-          // If stdout, redirect fd to /dev/null.
-          int null_fd = TEMP_FAILURE_RETRY(open("/dev/null", O_WRONLY));
-          ASSERT(null_fd >= 0);
-          VOID_TEMP_FAILURE_RETRY(dup2(null_fd, STDOUT_FILENO));
-          VOID_TEMP_FAILURE_RETRY(close(null_fd));
-        } else {
-          sd->Close();
-        }
+        sd->Close();
         socket_map_.Remove(GetHashmapKeyFromFd(fd), GetHashmapHashFromFd(fd));
         delete sd;
         DartUtils::PostInt32(msg[i].dart_port, 1 << kDestroyedEvent);