JavaScriptNode bufferSize

Hello group!

We discussed with Chris (off-list) the recent change from numberOfOutputs
to numberOfChannels in the createJavaScriptNode(), because I noticed my
sink.js was broken in the latest Chrome Canary.

I suggested that the first parameter (bufferSize) be optional as well,
reverting to default when passed undefined. In an advanced implementation,
this default could be adjusted to a value that the implementation deems a
good tradeoff between safety (avoiding underruns) and latency on that
system and setup. I believe Chris thinks this is a good idea, so he
suggested I bring this to discussion in the group so we can change the spec
if we agree on it.

Thoughts?

Cheers,
Jussi