Why doesn't Firefox have a checkbox on the dialog to just open the darn thing as a raw UTF-8 text in a new window, like what would happen if the content type were set properly?

No, I don't want to open the file with anything or save it.

Hey look, 19-year-old bug: https://bugzilla.mozilla.org/show_bug.cgi?id=196078

That bug is now an undergrad in college!

Does anyone have a recommendation on how to easily sandbox this to try it? I'd be hesitant to just compile and run obfuscated code like this, and in fact, I think the post and code both probably need a "warning, don't run this without confirming what it does" disclaimer.