CLJS-889: re-pattern works on strings containing \u2028 or \u2029

JavaScript RegExps don't match \u2028 or \u2029 with ., which was causing
the previous implementation of re-pattern to fail on those characters.
(It was as if the regexp was chopped short at the point where the offending
character appeared.)

Author: alexdowad

src/cljs/cljs/core.cljs

@@ -8405,8 +8405,9 @@ reduces them without incurring seq initialization"
   [s]
   (if (instance? js/RegExp s)
     s
-    (let [[_ flags pattern] (re-find #"^(?:\(\?([idmsux]*)\))?(.*)" s)]
-      (js/RegExp. pattern flags))))
+    (let [[prefix flags] (re-find #"^\(\?([idmsux]*)\)" s)
+          pattern (subs s (count prefix))]
+      (js/RegExp. pattern (or flags "")))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Printing ;;;;;;;;;;;;;;;;
 

test/cljs/cljs/core_test.cljs

@@ -937,7 +937,8 @@
     (is (= (re-seq (re-pattern "f(.)o") "foo bar foo baz foo zot") (list ["foo" "o"] ["foo" "o"] ["foo" "o"])))
     (is (= (re-matches (re-pattern "(?i)foo") "Foo") "Foo"))
                                         ; new RegExp("").source => "(?:)" on webkit-family envs, "" elsewhere
-    (is (#{"#\"\"" "#\"(?:)\""} (pr-str #"")))))
+    (is (#{"#\"\"" "#\"(?:)\""} (pr-str #"")))
+    (is (= (re-find (re-pattern "[\u2028]") " \u2028 ") "\u2028")))) ; regression test for CLJS-889
 
 (deftest test-destructuring
   (testing "Testing destructuring"