Added key that can return all elements that have a specific is-chunk() value.
Added key that can return all elements that have a specific is-chunk() value.

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