'Empty' tags with Multiple Domains module

Issue Summary

Hello,

Not sure if it is a bug, or maybe it's Multiple Domains' bug, but let's try ;)

When using Multiple Domains, Tagadelic shows up tags from all the domains in its cloud, not only from the used domain. Then 'empty' tag, when clicked, says there is no node for it, and it's true, because 'his' nodes belong to other domain.

So, in fact, when choosing any tag from cloud on the less popular domain, most of the tags give empty answer, making user stupid.