diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/bug729788.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/bug729788.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,25 @@
+var msPerDay = 86400000;
+function Day(t) {
+    return Math.floor(t / msPerDay);
+}
+function YearFromTime(t) {
+    sign = 1
+    year = sign < 0
+}
+function MonthFromTime(t) {
+    DayWithinYear(t)
+    function DayWithinYear(t) Day(t) - YearFromTime()
+    function WeekDay(t) {
+        weekday = Day(t) + 4
+        return (weekday < 0 ? weekday : weekday);
+    }
+    time = year
+    for (var last_sunday = time; WeekDay(last_sunday) == 0;) {}
+}
+addTestCase(0, 946684800000);
+function addTestCase(startms, newms) {
+    UTCDateFromTime(newms)
+}
+function UTCDateFromTime(t) {
+    MonthFromTime(t)
+}