Go doesn't omit empty parent tags for empty values[1], so we'll work
around this for now by creating a pointer to the property slice.
[1]: https://github.com/golang/go/issues/7233.
The Result Data field contains the test output that was read from stdin.
This used to be a chardata field, which escapes many characters in the
resulting XML. Writing this output with <![CDATA[]]> tags makes the raw
XML output much easier to read in e.g. a text editor.