Symfony 2.2 includes a new rendering strategy system to replace the old and rather crufty way of handling subreqests/ESI/hInclude. However, we're still using a clone of the old one. Let's get caught up.
This patch (as soon as I have a nid) drops most of the old HttpKernel class and switches the HtmlPageController over to use the inline rendering strategy. However, the AjaxController has code in it to handle an Ajax sub-response. I didn't want to rip that out yet, but the new rendering strategy logic only returns a string, nothing else. Blargh. I therefore kept our subclass but stripped it down to JUST the short forward() method. The old render() method (which we weren't using anyway) is gone.
That *may* be a problem for SCOTCH, though, since we wanted to return PartialResponse objects, not strings. I'm not entirely sure what Sam has in mind here, but tagging for SCOTCH anyway.