Also adjust the event handler's timer_fd to the monotonic clock.

runtime/bin/eventhandler_linux.cc

 // Copyright (c) 2012, 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 "platform/globals.h"
 #if defined(TARGET_OS_LINUX)
 
 #include "bin/eventhandler.h"
 #include "bin/eventhandler_linux.h"
 
@@ skipping 91 matching lines @@
   struct epoll_event event;
   event.events = EPOLLIN;
   event.data.ptr = NULL;
   int status = NO_RETRY_EXPECTED(epoll_ctl(epoll_fd_,
                                            EPOLL_CTL_ADD,
                                            interrupt_fds_[0],
                                            &event));
   if (status == -1) {
     FATAL("Failed adding interrupt fd to epoll instance");
   }
-  timer_fd_ = NO_RETRY_EXPECTED(timerfd_create(CLOCK_REALTIME, TFD_CLOEXEC));
+  timer_fd_ = NO_RETRY_EXPECTED(timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC));
   if (timer_fd_ == -1) {
     FATAL1("Failed creating timerfd file descriptor: %i", errno);
   }
   // Register the timer_fd_ with the epoll instance.
   event.events = EPOLLIN;
   event.data.fd = timer_fd_;
   status = NO_RETRY_EXPECTED(epoll_ctl(epoll_fd_,
                                        EPOLL_CTL_ADD,
                                        timer_fd_,
                                        &event));
@@ skipping 290 matching lines @@
 
 uint32_t EventHandlerImplementation::GetHashmapHashFromFd(intptr_t fd) {
   // The hashmap does not support keys with value 0.
   return dart::Utils::WordHash(fd + 1);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_LINUX)