CLJS-3239: Infinite analysis with dotted symbols

The analysis change for dotted symbols revealed a bug with import parsing.

`(:import goog)` would result in `:imports {goog goog}` in the ns analysis
map. Then when resolving a symbol like `goog.debug.Console`, the analyzer would
go into an infinite loop. This loop was in the `:import` branch of resolve-var.
This is because the expectation is that the value side of `:imports` map
is *different*.  But in this case, `{goog goog}`, it is not different, so the
analyzer would get stuck.

Notably, `(:import [goog])` doesn't have this problem.

Make `(:import goog)` match `(:import [goog])`

src/main/clojure/cljs/analyzer.cljc

@@ -2915,11 +2915,16 @@
                      (every? symbol? spec))
                 (and (symbol? spec) (nil? (namespace spec))))
     (throw (error env (parse-ns-error-msg spec "Only lib.ns.Ctor or [lib.ns Ctor*] spec supported in :import"))))
-  (let [import-map (if (sequential? spec)
+  (let [import-map (cond
+                     (sequential? spec)
                      (->> (rest spec)
                        (map #(vector % (symbol (str (first spec) "." %))))
                        (into {}))
-                     {(symbol (last (string/split (str spec) #"\."))) spec})]
+
+                     (not (== -1 (.indexOf (str spec) ".")))
+                     {(symbol (last (string/split (str spec) #"\."))) spec}
+
+                     :else {})]
     (doseq [[_ spec] import-map]
       (swap! deps conj spec))
     {:import  import-map

src/test/clojure/cljs/analyzer_tests.clj

@@ -1485,13 +1485,10 @@
             (:import [goog.history Html5History]))]))
     (is (some? (get-in @cenv [::ana/namespaces 'goog.history.Html5History :defs 'Html5History])))))
 
-(comment
-
+(deftest test-cljs-3239
   (let [cenv (env/default-compiler-env)]
     (env/with-compiler-env cenv
       (ana/analyze-form-seq
         '[(ns test.foo
-            (:import [goog.history Html5History]))]))
-    (get-in @cenv [::ana/namespaces 'goog.history.Html5History :defs]))
-
-  )
+            (:import goog))]))
+    (is (= {} (get-in @cenv [::ana/namespaces 'test.foo :imports])))))