CLJS-3419: JS Map & Set should return true for seqable? (#234)

src/main/cljs/cljs/core.cljs

@@ -2307,10 +2307,11 @@ reduces them without incurring seq initialization"
   "Return true if the seq function is supported for s"
   [s]
   (or
-   (nil? s)
-   (satisfies? ISeqable s)
-   (array? s)
-   (string? s)))
+    (nil? s)
+    (satisfies? ISeqable s)
+    (js-iterable? s)
+    (array? s)
+    (string? s)))
 
 (defn boolean
   "Coerce to boolean"

src/test/cljs/cljs/seqs_test.cljs

@@ -443,7 +443,7 @@
     (partition 5 [1 2 3]) ()
 
     (partition 4 4 [0 0 0] (range 10)) '((0 1 2 3) (4 5 6 7) (8 9 0 0))
-             
+
     (partition -1 [1 2 3]) ()
     (partition -2 [1 2 3]) ())
 
@@ -523,3 +523,9 @@
                     :initk initk)))]
       (= (into [] (src))
         (into [] (seq (src)))))))
+
+(deftest cljs-3419-seq-js-iterable
+  (let [js-set (js/Set. #js [1 2 3 4])
+        js-map (js/Map. #js [#js [1 2] #js [3 4]])]
+    (is (seqable? js-set))
+    (is (seqable? js-map))))