fixed error in the mockTheClock.js

Change-Id: I3b78fb708e97d3c27bd227af6b57be654bdbe83f
Reviewed-on: http://review.couchbase.org/30286
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>