Multiprocess tabs always crash, as first reported by the issue mentioned
below. It is now consistently reproducible both on NixOS and non-NixOS
for me, so I've decided to add a toggle to conveniently disable
multiprocess support as a work-around.
Closes https://github.com/NixOS/nixpkgs/issues/27759 but does
not really fix the underlying problem ...
The `extraPrefs` parameter is injected verbatim into the mozilla.cfg
file.
Note that the syntax is a superset of the usual prefs.js syntax. The
following procedures are of particular interest:
pref() to set a preference as if it had been toggled in about:config
defaultPref() to set the *default* value of a preference
lockPref() to set a preference & prevent further modification
clearPref() to reset a preference to its default state
Example:
```nix
tor-browser-bundle-bin.override {
extraPrefs = ''
// Increase default security level
pref("extensions.torbutton.security_slider", 2);
'';
}
```
