Add cljx rules for inconsistencies

We do something different when the multimethods dispatch on object
type. Because Javascript doesn't have classes, we dispatch using a
keyword instead.

src/cljx/clj_diff/core.cljx

@@ -1,6 +1,6 @@
 (ns clj-diff.core
   "Diff, patch and related functions for Clojure sequences."
-  (:require [clj-diff [miller :as miller]]))
+  (:require [clj-diff.miller :as miller]))
 
 (defn diff
   "Create the edit script for transforming sequance a into sequence b.
@@ -49,13 +49,16 @@
   patch will use the edit script to transform a into b.
 
   (diff a b) -> x, (patch a x) -> b."
-  (fn [s _] (class s)))
+  #+clj
+  (fn [s _] (class s))
+  #+cljs
+  (fn [s _] (when (string? s) :string)))
 
 (defmethod patch :default
   [s edit-script]
   (patch* s edit-script))
 
-(defmethod patch String
+(defmethod patch #+clj String #+cljs :string
   [s edit-script]
   (apply str (patch* s edit-script)))