[web-audio-api] Browser support tests

Hello,
I've created a small test suite to test and collect test results for Web
Audio API support in browsers:
http://www.doboism.com/projects/webaudio-compatibility/
The code is available at https://github.com/amitayd/webaudio-compatibility

It is intended to test the existence and structure of the API (currently a
subset of it). I've tried to make it in a way that will allow to declare a
larger portion of the API.

Would be happy to hear some feedback. I'd also like to hear if it is
something that should be integrated in the Web Platform tests. If so, any
suggestions as to what and how are be welcomed.

Cheers,
Amitay Dobo