Tweak iframe focusing edge-case
Tweak iframe focusing edge-case

Mostly this is just consistification, but technically this changes things so that non-HTML elements named "iframe" are no longer focusable. A follow-up to e0601820685ac8b2e5a2e94264e6eab6a0c0593c.

Joris-van-der-Wel/jsdom,tmpvar/jsdom,Zirro/jsdom,tmpvar/jsdom,mzgol/jsdom,mzgol/jsdom,mzgol/jsdom,Joris-van-der-Wel/jsdom,Zirro/jsdom,snuggs/jsdom,Joris-van-der-Wel/jsdom,snuggs/jsdom,fiftin/jsdom,fiftin/jsdom,fiftin/jsdom