changes to properly detect w3c Web Audio API, including some deprecated ...

...method names supported still in Safari.

Firefox 22 will implement the current w3c api specification, once this is released this summer both Chrome 7 Firefox will have compliant apis however we have no timeline for Safari to update ( and many mobile Safari browsers will be in the wild for some time ). Therefore, libraries supporting the web audio api will need to do feature detection to support both spec versions.