insecure form submission test page

When a page is loaded via HTTPS and does a form submission to an HTTP endpoint, the browser rightfully gives a security warning.

However, this warning is really appropriate when the destination host is on the HSTS preload list. The browser should be smart enough to know that it would use HTTPS for making the connection, and so skip the warning.

Here is a form that submits using HTTP to a site on the HSTS preload list, so the warning should not appear: