firefox: Add ALSA dependency for Web MIDI support

overlay/no-alsa.nix

@@ -4,7 +4,6 @@ let
   inherit (nixpkgs.lib.attrsets) genAttrs;
 in genAttrs [
   "SDL2"
-  "firefox-unwrapped"
   "mpv-unwrapped"
 ] (pkg: prev.${pkg}.override { alsaSupport = false; })
 // genAttrs [
@@ -12,6 +11,13 @@ in genAttrs [
   "libcanberra"
 ] (pkg: prev.${pkg}.override { withAlsa = false; })
 // {
+  firefox-unwrapped = (prev.firefox-unwrapped.overrideAttrs (prevAttrs: {
+    buildInputs = prevAttrs.buildInputs or [ ]
+      ++ [ final.alsa-lib ];
+  })).override {
+    alsaSupport = false;
+  };
+
   firefox = final.wrapFirefox final.firefox-unwrapped { };
 
   mpv = final.mpv-unwrapped.wrapper {