Send error-event if socket is marked for error.

runtime/bin/eventhandler_win.cc

Index: runtime/bin/eventhandler_win.cc
diff --git a/runtime/bin/eventhandler_win.cc b/runtime/bin/eventhandler_win.cc
index b6ac1ce2c75de5405b2b3602998bf45a5a09d95e..993670cc53e9ae9a705e5f818e7f3bfd4e156368 100644
--- a/runtime/bin/eventhandler_win.cc
+++ b/runtime/bin/eventhandler_win.cc
@@ -988,7 +988,9 @@ void EventHandlerImplementation::HandleInterrupt(InterruptMessage* msg) {
 
       Handle::ScopedLock lock(handle);
 
-      if (!handle->IsError()) {
+      if (handle->IsError()) {
+        DartUtils::PostInt32(msg->dart_port, 1 << kErrorEvent);
+      } else {
         if ((msg->data & ((1 << kInEvent) | (1 << kOutEvent))) != 0) {
           // Only set mask if we turned on kInEvent or kOutEvent.
           handle->SetPortAndMask(msg->dart_port, msg->data);