Provide a way to suppress implicit MIDL generation rules for actions

test/win/idl-rules/Window.idl

Index: test/win/idl-rules/Window.idl
diff --git a/test/msvs/buildevents/main.cc b/test/win/idl-rules/Window.idl
similarity index 66%
copy from test/msvs/buildevents/main.cc
copy to test/win/idl-rules/Window.idl
index 03c0285a6cc856103f8adad4d35dc76e42a51042..961b4638506f291a419624f01ed63d40f473a770 100644
--- a/test/msvs/buildevents/main.cc
+++ b/test/win/idl-rules/Window.idl
@@ -1,5 +1,9 @@
-// Copyright (c) 2014 Google Inc. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-int main() {}
+// Copyright (c) 2014 Google Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+[
+    WillBeGarbageCollected,
+] interface Window {
+    void alert();
+};