diff -r 000000000000 -r 6474c204b198 js/src/tests/Intl/extensions/options-value-emulates-undefined.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/Intl/extensions/options-value-emulates-undefined.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!xulRuntime.shell)
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/licenses/publicdomain/
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 843004;
+var summary =
+  "Use of an object that emulates |undefined| as the sole option must " +
+  "preclude imputing default values";
+
+print(BUGNUMBER + ": " + summary);
+
+if (typeof Intl !== 'object' && typeof quit == 'function') {
+  print("Test skipped");
+  reportCompare(true, true);
+  quit(0);
+}
+
+/**************
+ * BEGIN TEST *
+ **************/
+
+var opt = objectEmulatingUndefined();
+opt.toString = function() { return "long"; };
+
+var str = new Date(2013, 12 - 1, 14).toLocaleString("en-US", { weekday: opt });
+
+// Because "weekday" was present and not undefined (stringifying to "long"),
+// this must be a string like "Saturday" (in this implementation, that is).
+assertEq(str, "Saturday");
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);
+
+print("Tests complete");