timrwood/moment — pull request #629 by ichernev (2013-02-14 05:34:03+00:00)
Title: Fixed a bug in cloning a Date

To clone a Date object d you need to convert it to a Number first and then pass
it to Date constructor, like new Date(+d). Otherwise some browsers (firefox)
cut milliseconds.

Related to https://github.com/timrwood/moment/issues/625