Per requirement for the following link https://bugzilla.mozilla.org/show_bug.cgi?id=1282074#c5

If you want to expose this pref, please make sure that the user can't break everything with the pref.

I'd say that just having this preference is enough - I asked for it when I didn't know we had it in the first place. We don't really need to have it show up in about:config by default. Having it documented somewhere (probably worth starting a wiki page for magical graphics options) would be enough. That way we make sure the users that make the change are educated about what it does. We don't want somebody stumbling on this preference and changing the value without knowing what it does, and bricking their browser.