chromium{Beta,Dev}: Switch to LLVM 15

Not required yet but we should always use the latest LLVM version that
is available in Nixpkgs as Google builds Chromium against commits from
the main branch.

pkgs/applications/networking/browsers/chromium/default.nix

@@ -1,5 +1,7 @@
 { newScope, config, stdenv, fetchurl, makeWrapper
-, llvmPackages_14, ed, gnugrep, coreutils, xdg-utils
+, llvmPackages_14
+, llvmPackages_15
+, ed, gnugrep, coreutils, xdg-utils
 , glib, gtk3, gtk4, gnome, gsettings-desktop-schemas, gn, fetchgit
 , libva, pipewire, wayland
 , gcc, nspr, nss, runCommand
@@ -52,6 +54,9 @@ let
           inherit (upstream-info.deps.gn) url rev sha256;
         };
       });
+    } // lib.optionalAttrs (chromiumVersionAtLeast "111") rec {
+      llvmPackages = llvmPackages_15;
+      stdenv = llvmPackages_15.stdenv;
     });
 
     browser = callPackage ./browser.nix {