[web-audio-api] Make AudioBufferSourceNode.playbackRate read-only (#240)

> Originally reported on W3C Bugzilla [ISSUE-21629](https://www.w3.org/Bugs/Public/show_bug.cgi?id=21629) Mon, 08 Apr 2013 17:22:50 GMT
> Reported by Ehsan Akhgari [:ehsan]
> Assigned to 

I believe that the current non-readonly attribute is a mistake.

---
Reply to this email directly or view it on GitHub:
https://github.com/WebAudio/web-audio-api/issues/240