message: using promise response instead of done()
diff: @@ -241,15 +241,15 @@ describe("ToneBufferSource", () => {
  });
  }
  - it("schedules the onended callback when offline", (done) => {
  -
  + it("schedules the onended callback when offline", () => {
  + let wasInvoked = false;
  return Offline(() => {
  const player = new ToneBufferSource(buffer).toDestination();
  player.start(0.2).stop(0.4);
  - player.onended = () => {
  - done();
  - };
  - }, 0.5);
  + player.onended = () => wasInvoked = true;
  + }, 0.5).then(() => {
  + expect(wasInvoked).to.equal(true);
  + });
  });
  it("invokes the onended callback when a looped buffer is scheduled to stop", () => {
  