CLJS-485: RegExp flags are being dropped by string/replace

Changes clojure.string/replace-all to respect previously set RegExp
flags when creating new RegExp.

test for multiline

Author: jakemcc

src/main/cljs/clojure/string.cljs

@@ -26,7 +26,12 @@
 
 (defn- replace-all
   [s re replacement]
-  (.replace s (js/RegExp. (.-source re) "g") replacement))
+  (let [r (js/RegExp. (.-source re)
+                      (cond-> "g"
+                        (.-ignoreCase re) (str "i")
+                        (.-multiline re) (str "m")
+                        (.-unicode re) (str "u")))]
+    (.replace s r replacement)))
 
 (defn- replace-with
   [f]

src/test/cljs/clojure/string_test.cljs

@@ -25,7 +25,9 @@
     (is (= "FOObarFOO" (s/replace "foobarfoo" #"foo" s/upper-case)))
     (is (= "barbar)foo" (s/replace "foo(bar)foo" "foo(" "bar")))
     (is (= "FOO-ObarFOO-O"
-           (s/replace "foobarfoo" #"f(o)o" (fn [[m g1]] (s/upper-case (str m "-" g1)))))))
+           (s/replace "foobarfoo" #"f(o)o" (fn [[m g1]] (s/upper-case (str m "-" g1))))))
+    (is (= "faabarfaa" (s/replace "FOObarfoo" #"(?i)foo" "faa")))
+    (is (= "aaa\nccc" (s/replace "aaa\nbbb" #"(?m)^bbb" "ccc"))))
 
   (testing "Testing string join"
     (is (= "" (s/join nil)))