[opus] WebAssembly Opus Decoder

[Timothy B. Terriberry]

Chris McGowan wrote:
> container file.  What could we do to get MSE support for Ogg Opus 
> files?  I created this issue if it helps: 
> https://github.com/w3c/media-source/issues/245.  Would be happy to 
> initiate the process with the web platform folks.

Greg Maxwell had a proposal for adding Ogg to MSE from 2013:

https://www.w3.org/Bugs/Public/show_bug.cgi?id=22371

However, it was never finished, and Greg has not been with Mozilla for 
some time.