Fixes to <head> content model to make it determinist.
Fixes to <head> content model to make it determinist.

mushroomgithub/HTMLBook,oreillymedia/HTMLBook,gitenberg-dev/HTMLBook,oreillymedia/HTMLBook,gitenberg-dev/HTMLBook,gitenberg-dev/HTMLBook,macmillanpublishers/HTMLBook,mushroomgithub/HTMLBook,wastemobile/HTMLBook,oreillymedia/HTMLBook,mushroomgithub/HTMLBook,macmillanpublishers/HTMLBook,macmillanpublishers/HTMLBook,wastemobile/HTMLBook