CLJS-1297 defrecord does not emit IKVReduce protocol

Changed the setup for defrecord and provided a simple implementation of kvreduce. The implementation is copied from Clojure.
Also added one test.

Author: kamn

src/main/clojure/cljs/core.cljc

@@ -1867,6 +1867,9 @@
                                writer# pr-pair# ~pr-open ", " "}" opts#
                                (concat [~@(map #(core/list `vector (keyword %) %) base-fields)]
                                  ~'__extmap))))
+                        'IKVReduce
+                        `(~'-kv-reduce [this# f# init#]
+                           (reduce (fn [ret# [k# v#]] (f# ret# k# v#)) init# this#))
                         ])
                [fpps pmasks] (prepare-protocol-masks env impls)
                protocols (collect-protocols impls env)

src/test/cljs/cljs/new_new_test.cljs

@@ -80,6 +80,8 @@
             (map->Person {:firstname "Fred" :lastname "Mertz" :wife :ethel})))
       (is (= (dissoc ethel :husband)
             (map->Person {:firstname "Ethel" :lastname "Mertz"})))
+      (is (= (reduce-kv assoc {:age 30} fred)
+            {:age 30 :firstname "Fred" :lastname "Mertz"}))
       (is (= {:foo 'bar} (meta (with-meta (A.) {:foo 'bar}))))
       (is (= 'bar (:foo (assoc (A.) :foo 'bar))))
       (is (= (set (keys letters)) #{:a :b :c}))