UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce the problem:
1. Go to your site, typically something in production
2. Open the dev tools, sources panel
3. <Load local source map>

What is the expected behavior?
To be able to load an arbitrary, local source map for any site. Basically be able to debug in production without exposing your source map or use hacks like serving it from a special domain.

What went wrong?
This doesn't exists as far as I know.

Did this work before? No 

Chrome version: 56.0.2924.87  Channel: stable
OS Version: OS X 10.12.3
Flash Version: Shockwave Flash 24.0 r0

All other alternatives I know of require some sort of infrastructure, i.e. server side authentication/authorization of loading the source map. If you put `localhost` as your source map domain, you are just begging for an security exploit.

I think having the ability to use a local file would be the best solution, and could be seen as an extension of the current persistent workspace idea.