[whatwg] instantiating display:none plugins

[Robert O'Callahan]

I should add that the patch that uncovered this issue hasn't even landed on
Firefox nightlies yet (well, it was in one nightly and got reverted) so we
haven't had much testing. It seems unlikely we have found the only site
that's broken.

Rob
-- 
"If we claim to be without sin, we deceive ourselves and the truth is not
in us. If we confess our sins, he is faithful and just and will forgive us
our sins and purify us from all unrighteousness. If we claim we have not
sinned, we make him out to be a liar and his word is not in us." [1 John
1:8-10]