Ignore nodes with no text name, value and description.

This is in order to skip certain nodes that usually only carry
structural information (such as ListItem nodes). However, because of the
flattening, this structural information is never used on iOS, so we can
just skip the accessible node completely.

Change-Id: I17018c6565f8b39831f2d2944422c6670a438ab9
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>