Any way to mitigate dist size growth

Hey,

I've been playing about with grpc-web and there some threads around the [dist size](https://github.com/grpc/grpc-web/issues/270) already, but their concern was around the base dist using the lightweight hello world example.

Is there a best approach to combating the dist size as the needs grow? E.g. You're defining 300 messages and beyond?

Based on the generated client code so far, I'm guessing all defined messages are linked to the generated code and are included in the dist regardless?