You have JavaScript. You need a bookmarklet. This does that.
manifestR is a bookmarklet, which you drag to your bookmarks bar. Then, when you visit any page, you can click the manifestR button, and it will create an HTML5 appcache manifest file for that page.
DOM Monster is a cross-platform, cross-browser bookmarklet that will analyze the DOM & other features of the page you're on, and give you its bill of health.
It displays a menu with links that load other bookmarklets including Firebug Lite, Page Resources, DOM Monster, SpriteMe, and CSSess. The Mobile Perf menu is updated as new bookmarklets are released - so you get the latest tools automatically.