Remove support for old Mozilla Audio Data API which is not longer available in Firefox.
Remove the use of Web Audio API ScriptProcessorNode for queueing buffers. It doesn't improve in practice, generates a new set of compatibility bugs and is limited to one sampling frequency only (which the browser either matches or doesn't match at random). Keep the code simple and use a unified path for SDL audio in all audio frequencies.
Improve SDL audio queueing to not only rely on setTimeout()s to queue new audio data, but also try to queue new audio at the end of each requestAnimationFrame. Since rAFs fire at every 16 msecs tied to vsync interval, this should give a much better granularity for audio streaming.
Reduce the SDL buffering delay to 50msecs to make the audio latency smaller.
Merge pull request #2651 from juj/raf_sdl_queue

requestAnimationFrame-based SDL audio queue.