It depend on what you mean by "integrate". Mozilla/Firefox had the extensions ecosystem that produced a bunch of interesting tools, which eventually crystalliz

It depend on what you mean by "integrate". Mozilla/Firefox had the extensions ecosystem that produced a bunch of interesting tools, which eventually crystallized as Firebug: http://flailingmonkey.com/the-history-of-firebug http://flailingmonkey.com/the-history-of-firebug