Join embeder threads on Windows.

runtime/bin/main.cc

Index: runtime/bin/main.cc
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index 4e2b24acce608c4e11f99cce29d897f7384bef8b..5b2c70b9c37aed5d9a58c8ff9efaf35bfc00f446 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -110,6 +110,8 @@ static void ErrorExit(int exit_code, const char* format, ...) {
 
   Dart_Cleanup();
 
+  DebuggerConnectionHandler::StopHandler();
+  EventHandler::Stop();
   exit(exit_code);
 }
 
@@ -1042,6 +1044,8 @@ void main(int argc, char** argv) {
                        DartUtils::EntropySource)) {
     fprintf(stderr, "%s", "VM initialization failed\n");
     fflush(stderr);
+    DebuggerConnectionHandler::StopHandler();
+    EventHandler::Stop();
     exit(kErrorExitCode);
   }
 
@@ -1066,6 +1070,8 @@ void main(int argc, char** argv) {
     Log::PrintErr("%s\n", error);
     free(error);
     delete [] isolate_name;
+    DebuggerConnectionHandler::StopHandler();
+    EventHandler::Stop();
     exit((exit_code != 0) ? exit_code : kErrorExitCode);
   }
   delete [] isolate_name;
@@ -1171,6 +1177,9 @@ void main(int argc, char** argv) {
 
   Dart_Cleanup();
 
+  DebuggerConnectionHandler::StopHandler();
+  EventHandler::Stop();
+
   // Free copied argument strings if converted.
   if (argv_converted) {
     for (int i = 0; i < argc; i++) free(argv[i]);