It should be feasible. I've got multiple bookmarklets that do this for downloading blogs and webcomics for later offline reading (some are so heavily scripted it's impossible to just fetch them).
Add something to the above so that it inlines referenced files in base64, and you're basically done (I tend not to bother as I'm only after the text content). For actually interactive files, it gets more complicated; you'll need to save the current JavaScript state as well as the page resources.
```saveAs(window.title+".html","<html>"+document.head.outerHTML+document.body.outerHTML+"</html>")```
Add something to the above so that it inlines referenced files in base64, and you're basically done (I tend not to bother as I'm only after the text content). For actually interactive files, it gets more complicated; you'll need to save the current JavaScript state as well as the page resources.