add :nohighlight t to use helm-rg faces

helm-rg.el

@@ -2354,13 +2354,12 @@ will be split!"
 
 ;; Helm sources
 (defconst helm-rg-process-source
-  ;; `helm-grep-ag-class' is provided by `helm' -- I don't know if that identifier is stable but if
-  ;; it's not it will error out very quickly (because `helm-make-source' will fail if that symbol
-  ;; is removed).
   (helm-make-source "ripgrep" 'helm-source-async
     ;; FIXME: we don't want the header to be hydrated by helm, it's huge and blue and
     ;; unnecessary. Do it ourselves, then we don't have to delete the header in
     ;; `helm-rg--freeze-header-for-bounce'.
+    :nohighlight t
+    :nomark t
     :header-name #'helm-rg--header-name
     :keymap 'helm-rg-map
     :history 'helm-rg--input-history