Thanks very much for the quick response.
But we can't support older devices/webkits anyway (with or without cordova, because for audio, cordova's media plugin is incapable of what we're doing with the Web Audio API that's built into recent versions of webkit/Firefox).
I guess the question is this: I want to use the browser implementation of IndexedDB and avoid cordova plugins as much as possible, not only because they are unnecessary for the above reason, but also for other good reasons. Cordova does not strip the webkit version it uses of functionality like AudioAPI or IndexedDB, right? It'll still be there when we use cordova to create a native-like hybrid app? I'll just test it out and will report if there are any problems.