Fix x-value for OOXML charts if the x-value wasn't provided from a sheet-reference but from the internal cache.
Before in such cases we set the m_countXValues to the correct value but still added the empty value to our m_domainValuesCellRangeAddress list and later wrote two chart:domain's for the x-value where the first one was empty.
That doesn't only violate the standard but also lead to wrong (aka empty) values for the x-dataregion in such cases what lead to all kind of interesting side-effects.