refactor(firefox-gx): fetch src from flake inputs

home/firefox/default.nix

@@ -1,13 +1,16 @@
 {
   config,
   pkgs,
+  firefox-gx-src,
   ...
 }: let
   inherit (builtins) readFile;
   firefox-addons = pkgs.recurseIntoAttrs (pkgs.callPackage ./addons {});
   sound-volume = firefox-addons."600-sound-volume";
 
-  firefox-gx = pkgs.callPackage ./firefox-gx {};
+  firefox-gx = pkgs.callPackage ./firefox-gx {
+    inherit firefox-gx-src;
+  };
 in {
   home.file = {
     ".mozilla/firefox/matt/chrome/components".source = "${firefox-gx}/chrome/components";

home/firefox/firefox-gx/default.nix

@@ -1,18 +1,13 @@
 {
   lib,
   stdenvNoCC,
-  fetchFromGitHub,
+  firefox-gx-src,
 }:
-stdenvNoCC.mkDerivation rec {
+stdenvNoCC.mkDerivation {
   pname = "firefox-gx";
-  version = "9.0";
+  version = firefox-gx-src.rev;
 
-  src = fetchFromGitHub {
-    owner = "Godiesc";
-    repo = pname;
-    rev = "v${version}";
-    sha256 = "sha256-FCx5mADqrjAN27lLaZViOFGUNDg/2jpern8sem8u49w=";
-  };
+  src = firefox-gx-src;
 
   installPhase = ''
     # Personal changes