Fix bug in string replace with nonparticipating captures.

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 ea6912724399bd37d99cd1d72ab1a33576f29616..a555c203cc847e4d98edb98c684b6dca91f22c53 100644
--- a/test/mjsunit/string-replace.js
+++ b/test/mjsunit/string-replace.js
@@ -178,13 +178,16 @@ longstring = longstring + longstring;
 longstring = longstring + longstring;
 // longstring.length == 5 << 11
 
-replaceTest(longstring + longstring, 
+replaceTest(longstring + longstring,
             "<" + longstring + ">", /<(.*)>/g, "$1$1");
-            
+
 replaceTest("string 42", "string x", /x/g, function() { return 42; });
-replaceTest("string 42", "string x", /x/, function() { return 42; });            
+replaceTest("string 42", "string x", /x/, function() { return 42; });
 replaceTest("string 42", "string x", /[xy]/g, function() { return 42; });
 replaceTest("string 42", "string x", /[xy]/, function() { return 42; });
 replaceTest("string true", "string x", /x/g, function() { return true; });
 replaceTest("string null", "string x", /x/g, function() { return null; });
-replaceTest("string undefined", "string x", /x/g, function() { return undefined; });            
+replaceTest("string undefined", "string x", /x/g, function() { return undefined; });
+
+replaceTest("aundefinedbundefinedcundefined", 
+            "abc", /(.)|(.)/g, function(m, m1, m2, i, s) { return m1+m2; });