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 5c36f41abee04c0ac518f95a8328b615e666fe24..547be0d0f6a61fc4040744d8b7d5c5f5b6c4e60d 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);
 }
 
@@ -1038,6 +1040,8 @@ void main(int argc, char** argv) {
                        DartUtils::EntropySource)) {
     fprintf(stderr, "%s", "VM initialization failed\n");
     fflush(stderr);
+    DebuggerConnectionHandler::StopHandler();
+    EventHandler::Stop();
     exit(kErrorExitCode);
   }
 
@@ -1062,6 +1066,8 @@ 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;
@@ -1167,6 +1173,9 @@ 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]);