Blackboxing JS files is now possible in Firefox
https://developer.mozilla.org/en-US/docs/Tools/Debugger
And in Chrome Canary using Experimental Dev tools.
http://www.divshot.com/blog/tips-and-tricks/ignoring-library-code-while-debugging-in-chrome/
Update. In Chrome v.75 there is a separabe tab for blackboxing.
Above works in stable Chrome build as well now.