XamlParseException is thrown when importing revision date time of track changes which is exported with different than invariant culture.

Steps to reproduce: 
Set the current thread culture to "new CultureInfo("nb-NO")"
Turn on track changes.
Start the RTB and enter some text.
Export to XAML.
Import the previously exported XAML file.
Observed result:  XamlParseException is thrown when parsing the revision date time object.



Available in LIB version: 2017.1.418