> Just for the record there are several open source 
> javascript engines, SpiderMonkey from the mozilla 
> project <http://www.mozilla.org/js/spidermonkey/> that 
> has been used in several non Mozilla browser 
projects:
> <http://www.mozilla.org/js/projects.html>

Yes.. but this would require huge work, as the 
javascript engine would have to work in standalone 
mode (no user interaction). Besides many javascript 
pages will continue NOT to work, because executing a 
page/downloading links does not mean making a working 
local page. 
Example: foo.src=http://'+bar+'.gif
will never be replaced properly, except if you add an 
articial intelligence module ;)