Using The Mozilla Source Server
Using the Mozilla source server is now even more feature-packed. The nightly debug builds are now also Source Indexed so that by following a couple of simple steps you can also have the source code served to you for debugging without a local build.
What you’ll need
WinDbg or Visual Studio (not Code)
A nightly build; go to the /pub/firefox/nightly/latest-mozilla-central/ folder and grab the installer
Set up symbols
Follow the instructions for Using the Mozilla symbol server. Once the symbol path is set you must now enable Source Server.
Using the source server in WinDbg
In the WinDbg command line, type .srcfix
and hit enter. This enables
source server support.
Using the source server in Visual Studio
Enable source server support under Tools -> Options. Also, disable (uncheck) the box that says “Require source files to exactly match the original version”.