as I understand it, you can do the trick as follows:
cache.manifest is a file generated using PHP, in the first generation it returns a list of files less than 5 MB and sets the cookie flag. the client side of the script on 'cached' checks if a cookie is set and calls window.applicationCache.update() , so the PHP code starts again, it checks if a cookie is set and returns the full cache.manifest file, updates the cookie flag
source share