Do you even know that this is invalid and the proper tag is called just <nav>? Do you know that <title> must not be empty in the initial page? Do you know that custom attributes must start with data- (not ng- or ui-)?
I honestly don't understand how did the authors manage to make a skeleton (!) page not passing validation. Even <title> is empty when it must not be so.
Is it because of Angular? Well, if a framework forces you to write invalid HTML (tags, attributes, whatever), it sucks, no matter what.
<navbar></navbar>
Do you even know that this is invalid and the proper tag is called just <nav>? Do you know that <title> must not be empty in the initial page? Do you know that custom attributes must start with data- (not ng- or ui-)?
Did you even check your page with http://validator.w3.org?