Firefox warnings coming from bcsocket-uncompressed.js

Firefox is warning `Attempt to set a forbidden header was denied: Connection` which points to bcsocket-uncompressed.js in my bundled code.

I believe it's coming from this line:
https://github.com/josephg/node-browserchannel/blob/master/dist/bcsocket-uncompressed.js#L1792

I'm not sure what dependency is adding that or if/how it should be fixed. If one of the maintainers can point me in the right direction I'll open an issue on the actual offending library's issue tracker instead of here.