diff -r 000000000000 -r 6474c204b198 js/src/tests/ecma_5/Date/fractions.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/ecma_5/Date/fractions.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,24 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommonn.org/licenses/publicdomain/
+ */
+
+var BUGNUMBER = 771946;
+var summary = "Fractional days, months, years shouldn't trigger asserts";
+
+print(BUGNUMBER + ": " + summary);
+
+/**************
+ * BEGIN TEST *
+ **************/
+
+new Date(0).setFullYear(1.5);
+new Date(0).setUTCDate(1.5);
+new Date(0).setMonth(1.5);
+
+/******************************************************************************/
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);
+
+print("Tests complete");