Fix wrong test in r13766 (Insert conversion to string in string.replace).

test/mjsunit/string-replace.js

Index: test/mjsunit/string-replace.js
diff --git a/test/mjsunit/string-replace.js b/test/mjsunit/string-replace.js
index d9a274d57fb0035d6eeaca636ae554e8110c12d1..de921155759cc5fd3477113727a8a44c393f1ab7 100644
--- a/test/mjsunit/string-replace.js
+++ b/test/mjsunit/string-replace.js
@@ -225,7 +225,7 @@ var side_effect_flag = false;
 var replace_obj_side_effects = {
     toString: function() { side_effect_flag = true; return "x" }
 }
-assertEquals("abc", "abc".replace(/z/g, function() { return "x"; }));
+assertEquals("abc", "abc".replace(/z/g, replace_obj_side_effects));
 assertTrue(side_effect_flag);  // Side effect triggers even without a match.
 
 var regexp99pattern = "";