I can duplicate that in IE8 by going to Page/Style/No Style. This works the same way in Firefox. My memory is this capability has been around in browsers for years, but I've never figured out a good use for it. If the web developer wanted, they could set up multiple styles to allow you to choose the one you prefer. I think "no style" strips out a lot of the formatting.

edit to add:

On closer inspection, what I get is similar, but not exactly the same.