Unless I'm totally missing the point of the instant search feature, this is definitely something you can do in Emacs[1], and something I believe I've seen co-workers do in Sublime.
At a cursory glance, I'm not sure it is the same. Brackets keeps some type of index. So there is zero delay whenever you perform a project wide search.
Looks like Emacs helm uses Silver Searcher which is real time, but impressively fast.
[1] https://github.com/syohex/emacs-helm-ag