CLJS-1416: cljs.util/last-modified leaks files

Author: swannodette

src/main/clojure/cljs/util.cljc

@@ -142,7 +142,14 @@
 (defn last-modified [src]
   (cond
     (file? src) (.lastModified ^File src)
-    (url? src) (.getLastModified (.openConnection ^URL src))
+    (url? src)
+    (let [conn (.openConnection ^URL src)]
+      (try
+        (.getLastModified conn)
+        (finally
+          (let [ins (.getInputStream conn)]
+            (when ins
+              (.close ins))))))
     :else
     (throw
       (IllegalArgumentException. (str "Cannot get last modified for " src)))))