Don't treat stdin from a terminal differently from piped input

runtime/bin/eventhandler_macos.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 <errno.h>
 #include <poll.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <string.h>
 #include <sys/time.h>
@@ skipping 223 matching lines @@
     if ((pollfd->revents & POLLIN) != 0) {
       if (FDUtils::AvailableBytes(pollfd->fd) != 0) {
         event_mask = (1 << kInEvent);
       } else if (((pollfd->revents & POLLHUP) != 0)) {
         event_mask = (1 << kCloseEvent);
         sd->MarkClosedRead();
       } else if ((pollfd->revents & POLLERR) != 0) {
         event_mask = (1 << kErrorEvent);
       } else {
         if (sd->IsPipe()) {
-          // For stdin when reading from a terminal treat POLLIN with 0
-          // available bytes as end-of-file.
-          if (sd->fd() == STDIN_FILENO && isatty(sd->fd())) {
+          // When reading from stdin (either from a terminal or piped
+          // input) treat POLLIN with 0 available bytes as
+          // end-of-file.
+          if (sd->fd() == STDIN_FILENO) {
             event_mask = (1 << kCloseEvent);
             sd->MarkClosedRead();
           }
         } else {
           // If POLLIN is set with no available data and no POLLHUP use
           // recv to peek for whether the other end of the socket
           // actually closed.
           char buffer;
           ssize_t bytesPeeked = recv(sd->fd(), &buffer, 1, MSG_PEEK);
           if (bytesPeeked == 0) {
@@ skipping 111 matching lines @@
     FATAL("Create start event handler thread");
   }
 }
 
 
 void EventHandlerImplementation::SendData(intptr_t id,
                                           Dart_Port dart_port,
                                           intptr_t data) {
   WakeupHandler(id, dart_port, data);
 }