See current development here.
This document proposes a new resource batch file format, together with a concept of preloading resource batches on the Web. This proposal is derived from Web Bundles by Jeffrey Yasskin and dynamic bundle serving by Yoav Weiss, with significant input from Pete Snyder, who raised concerns about Web Bundles.
When loading subresources on the Web, developers currently have an unfortunate choice between serving resources individually, or using bundlers, both of which have disadvantages which hurt loading performance. This document proposes a new mechanism, "resource batch preloading", which allows subresources to be loaded