revert cljs.closure/compile-file "optimization", must always populate

compilation environment with analysis information, not doing so
damages composition of namespaces with smaller compilation units like
expressions. the problem was uncovered by starting REPLs with cached
files, the second run would be borked because we compiled core but did
not populate the compilation environment.

Include comment covering this point as well.

Author: swannodette

src/clj/cljs/compiler.clj

@@ -1125,7 +1125,13 @@
                           {:recompile (into recompile (ana/ns-dependents ns))
                            :visited   (conj visited ns)})))
                     ret))
-                ns-info))
+                (do
+                  ;; always populate compilation environment with analysis information
+                  ;; while it would seem this isn't necessary avoiding to do so damages
+                  ;; composition of smaller compilation units like expressions (i.e. REPLs)
+                  (when-not (contains? (::ana/namespaces @env/*compiler*) ns)
+                    (with-core-cljs opts (fn [] (ana/analyze-file src-file opts))))
+                  ns-info)))
             (catch Exception e
               (throw (ex-info (str "failed compiling file:" src) {:file src} e))))
           (throw (java.io.FileNotFoundException. (str "The file " src " does not exist."))))))))