We currently have lexical binding enabled in emms-info-exiftool,
emms-info-tinytag, and emms-playlist-limit.
I'm going to add the lexical-binding header to the rest of the Emms
code. Being between releases, now is the right time to do so. But I'll
wait a week in case anyone wants to write in and give me a good reason
After the move to lexical binding it would be great if people use Emms
from the git repo a bit to make sure that it didn't mysteriously break
anything. It really shouldn't, but who knows.