CLJS-1583: (hash (symbol "/")) does not match (hash '/)

Modify symbol function to correctly handle "/" corner-case,
and add tests comparing properties of '/ vs (symbol "/").

Author: DaoWen

src/main/cljs/cljs/core.cljs

@@ -978,7 +978,7 @@
    (if (symbol? name)
      name
      (let [idx (.indexOf name "/")]
-       (if (== idx -1)
+       (if (< idx 1)
          (symbol nil name)
          (symbol (.substring name 0 idx)
                  (.substring name (inc idx) (. name -length)))))))

src/test/cljs/cljs/core_test.cljs

@@ -302,6 +302,11 @@
   (testing "Testing symbol ctor is idempotent"
     (is (= 'a (symbol 'a))))
 
+  (testing "Testing constructed division symbol"
+    (is (= '/ (symbol "/")))
+    (is (= (namespace '/) (namespace (symbol "/"))))
+    (is (= (hash '/) (hash (symbol "/")))))
+
   (testing "Testing keyword ctor"
     (is (= :a (keyword "a")))
     (is (= :a (keyword 'a)))