We could create a new parser. Clear does essentially the same thing though as it resets the state back to the start so you essentially have a new parser. I originally made this change for `NodeVTT` so that we don't have to create a new PhantomJS instance every time we start parsing a new file, but that line of logic was wrong because we can still just create a new parser. I'm still trying to fit my head around PhantomJS a bit.

It lets you start parsing a new stream without creating a new parser. I'm not sure if that's needed though. I don't have a strong opinion on it anymore. Thoughts @humphd ?