Although that's cheating, you can achieve the same effect by creating the glyph and replacing any letter that's only used once (O, H or E in this case) with it. The other characters in the font can be blank. Therefore it works both for those that interpret it visually, and those that interpret the text.
I've seen this suggested for replacing a brand name with a logotype.
Is that why it requires js, and looks like "Back < & Future" if js is disabled?
There is no JS whatsoever on the page. And it still looks correct in Safari when JS is disabled.
The font is specified in the CSS with @font-face, a CSS2 feature. Perhaps the browser you're using might implement this feature using JS.