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 502a7a4bd4a270369b933d7a6dcf7a71bc553586..cc122b2d0dd2eeac737bf8eaa7cbb06b83abda6e 100644
--- a/test/mjsunit/string-replace.js
+++ b/test/mjsunit/string-replace.js
@@ -216,10 +216,18 @@ assertEquals('She sells sea$schells by the sea$schore.',
 
 var replace_obj = { length: 0, toString: function() { return "x"; }};
 assertEquals("axc", "abc".replace(/b/, replace_obj));
+assertEquals("axc", "abc".replace(/b/g, replace_obj));
 
 var search_obj = { length: 1, toString: function() { return "b"; }};
 assertEquals("axc", "abc".replace(search_obj, function() { return "x"; }));
 
+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"; }));
+assertTrue(side_effect_flag);  // Side effect triggers even without a match.
+
 var regexp99pattern = "";
 var subject = "";
 for (var i = 0; i < 99; i++) {