Revert "just to see if this is it"

This reverts commit 21a427a.

Author: borkdude

src/nextjournal/clerk/viewer.cljc

@@ -45,9 +45,7 @@
      (get-type [_] :val)))
 
 (defn render-fn? [x]
-  #?(:clj (and (some? x)
-               (str/includes? (.getName (class x)) "RenderFn"))
-     :cljs (instance? RenderFn x)))
+  (instance? RenderFn x))
 
 (defn render-eval? [x]
   (and (render-fn? x)