CLJS-2250: Support :foreign-libs overrides via :provides

Author: swannodette

src/main/clojure/cljs/closure.clj

@@ -1996,7 +1996,7 @@
                 (conj (string/replace p' "_" "-")))))
           (expand-lib* [{:keys [file] :as lib}]
             (if-not file
-              [] ;; foreign-lib override case - David
+              [lib] ;; foreign-lib override case - David
               (let [root (.getAbsolutePath (io/file file))
                     dir (io/file file)]
                 (if (.isDirectory dir)

src/main/clojure/cljs/js_deps.cljc

@@ -164,7 +164,7 @@ case."
                          index provides)
                        index)]
         (if (:foreign dep)
-          (if-let [file (get-file dep index)]
+          (if-let [file (get-file dep index')]
             (update-in index' [file] merge dep)
             (throw
               (Exception.