CLJS-2242: Lots of undeclared Var warns in cljs.spec.gen.alpha

Revert last commit. We must analyze deps before loading requires.

Instead update c.a/analyze-deps to check js-module-exists?

Author: swannodette

src/main/clojure/cljs/analyzer.cljc

@@ -2103,6 +2103,7 @@
          (when-not (or (not-empty (get-in compiler [::namespaces dep :defs]))
                        (contains? (:js-dependency-index compiler) (name dep))
                        (contains? (:node-module-index compiler) (name dep))
+                       (js-module-exists? (name dep))
                        #?(:clj (deps/find-classpath-lib dep)))
            #?(:clj (if-some [src (locate-src dep)]
                      (analyze-file src opts)

src/main/clojure/cljs/repl.cljc

@@ -493,9 +493,11 @@
        ;; NOTE: means macros which expand to ns aren't supported for now
        ;; when eval'ing individual forms at the REPL - David
        (when (#{:ns :ns*} (:op ast))
-         (load-dependencies repl-env
-           (into (vals (:requires ast)) (distinct (vals (:uses ast))))
-           opts))
+         (let [ast (ana/no-warn (ana/analyze env form nil opts))]
+           (load-dependencies repl-env
+             (into (vals (:requires ast))
+               (distinct (vals (:uses ast))))
+             opts)))
        (when *cljs-verbose*
          (err-out (println wrap-js)))
        (let [ret (-evaluate repl-env filename (:line (meta form)) wrap-js)]