Polish the removal of EventHandler cleanup in r26517.

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 20c6b61383fc5e586ad348c72bfe093885a3c6de..8964e3b28e1833051cda2a9af37961d3a7a8ab01 100644
--- a/runtime/bin/eventhandler_macos.cc
+++ b/runtime/bin/eventhandler_macos.cc
@@ -186,7 +186,7 @@ void EventHandlerImplementation::WakeupHandler(intptr_t id,
   msg.data = data;
   // WriteToBlocking will write up to 512 bytes atomically, and since our msg
   // is smaller than 512, we don't need a thread lock.
-  // See: http://linux.die.net/man/7/pipe, section 'Pipe_buf'.
+  ASSERT(kInterruptMessageSize < PIPE_BUF);
   intptr_t result =
       FDUtils::WriteToBlocking(interrupt_fds_[1], &msg, kInterruptMessageSize);
   if (result != kInterruptMessageSize) {