diff -r 000000000000 -r 6474c204b198 js/src/tests/ecma_3/Array/regress-619970.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/ecma_3/Array/regress-619970.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,8 @@
+function test() {
+    delete arguments[1];
+    return Array.prototype.join.call(arguments);
+}
+assertEq(test(1,2,3), "1,,3");
+Object.prototype[1] = "ponies!!!1";
+assertEq(test(1,2,3), "1,ponies!!!1,3");
+reportCompare(true,true);