Added support for post version 3.0 which doesn't come with name info.

I‘m not 100% sure if I made it correctly. I was working on some fonts with postscript table version 3.0, which opentype.js doesn't support. So I added another branch in the version switch. And [the spec says](https://www.microsoft.com/typography/OTSPEC/post.htm) it might not come with a names table.