I've spent several hours in the past year trying to debug a frustrating error with the vmware Web UI for Linux. This UI relies on running iceweasel (aka Firefox) on the VM host machine. I think I finally solved the problem today, after much tooth gnashing.
To fix, I changed the URL to https://dzur:8333/ui/, where dzur is the local public name of my VM host, and reloaded. After reconfirming the security exception in Firefox, the UI loaded.
I think this is probably a bug in Firefox; at the very least it should warn you that it's not letting certain JS files be loaded because of an invalid security cert.
Anyway, I'm posting this so that hopefully I can save others the time, energy, and headache of figuring this out for themselves. It took me far too long.