mozilla/webvtt — pull request #152 by caitp (2013-02-22 15:53:24+00:00)
Title: Only enter `finish` branch in `webvtt_lex` if characters have been read.

We should avoid entering this branch otherwise, because it can lead to the return of an incorrect token identifier.

Avoiding it ensures that `UNFINISHED` is returned rather than `BADTOKEN`, which is kind of a hint to the program that we've reached the end.