anchor.diff:  , yasm, mesa, sqlite, unzip, makeWrapper
   , hunspell, libevent, libstartup_notification, libvpx
   , cairo, gstreamer, gst-plugins-base, icu, libpng, jemalloc, libpulseaudio
  -, autoconf213, which
  +, autoconf213, which, cargo, rustc
   , writeScript, xidel, common-updater-scripts, coreutils, gnused, gnugrep, curl
   , enableGTK3 ? false, gtk3, wrapGAppsHook
   , debugBuild ? false
  
positive.code:     ++ lib.optional enableGTK3 gtk3
      ++ lib.optionals (!passthru.ffmpegSupport) [ gstreamer gst-plugins-base ];
  
    nativeBuildInputs = [ autoconf213 which gnused pkgconfig perl python ] ++ lib.optional enableGTK3 wrapGAppsHook;
  
    configureFlags =
      [ "--enable-application=browser"
  
negative.code: 
    firefox-unwrapped = common {
      pname = "firefox";
      version = "53.0";
      sha512 = "36ec810bab58e3d99478455a38427a5efbc74d6dd7d4bb93b700fd7429b9b89250efd0abe4609091483991802090c6373c8434dfc9ba64c79a778e51fd2a2886";
      updateScript = import ./update.nix {
        attrPath = "firefox-unwrapped";
        inherit writeScript lib common-updater-scripts xidel coreutils gnused gnugrep curl;
  