Fix HTTP sample implementation to actually wait for connections before attempting to write.

runtime/bin/eventhandler_linux.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 197 matching lines @@
     printf("(and %08x) ", pollfd->revents & ~all_events);
   }
   printf("(available %d) ", FDUtils::AvailableBytes(pollfd->fd));
 
   printf("\n");
 }
 #endif
 
 intptr_t EventHandlerImplementation::GetPollEvents(struct pollfd* pollfd) {
 #ifdef DEBUG_POLL
-  printf("Poll events:\n");
   if (pollfd->fd != interrupt_fds_[0]) PrintEventMask(pollfd);
 #endif
   intptr_t event_mask = 0;
   SocketData* sd = GetSocketData(pollfd->fd);
   if (sd->IsListeningSocket()) {
     // For listening sockets the POLLIN event indicate that there are
     // connections ready for accept unless accompanied with one of the
     // other flags.
     if ((pollfd->revents & POLLIN) != 0) {
       if ((pollfd->revents & POLLHUP) != 0) event_mask |= (1 << kCloseEvent);
@@ skipping 143 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);
 }