The problem due to the deprecation of ArraySelectionInformationHelper. That
helper ensured that the number-of-elements-per-command was set correctly on the
property when information was fetched. That being set was essential for any
dependent domains. This was no longer being set since the information helper
disappeared. So added check to vtkSMStringVectorProperty::ReadXMLElements() to
ensure that the number-of-elements-per-command is updated when a
ArraySelectionInformationHelper is detected in the XML.