Fix code for handling backrefs to date objects.
Fix code for handling backrefs to date objects.

The code was testing the wrong typecode.

LivingLogic/LivingLogic.Javascript.ul4,doerwalter/LivingLogic.Javascript.ul4,doerwalter/LivingLogic.Javascript.ul4,LivingLogic/LivingLogic.Javascript.ul4