Major Description
JavaScriptFilteredIntoFooterHeaderResponse creates two buckets. One for CSS and one for JS. The current logic is that everything that isn't CSS must be JS and so gets put at the bottom of the page. This breaks if CssAcceptingHeaderResponseFilter mistakingly identifies something as non-CSS (eg a CSS file with another extension). Also everything else that isn't CSS gets put into the footer bucket (which should contain only JS).
It would be better if it only puts things in the footer bucket if it can determine that it's JS and sort everything else into the header bucket.