message: OfflineContext can take a OfflineAudioContext in constr
diff: @@ -25,16 +25,19 @@ export class OfflineContext extends Context {
  */
  protected _context!: OfflineAudioContext;
  - constructor(channels: number, duration: Seconds, sampleRate: number) {
  + constructor(channels: number | OfflineAudioContext, duration: Seconds, sampleRate: number) {
  super({
  clockSource: "offline",
  - context: new OfflineAudioContext(channels, duration * sampleRate, sampleRate),
  + context: channels instanceof OfflineAudioContext ?
  + channels : new OfflineAudioContext(channels, duration * sampleRate, sampleRate),
  lookAhead: 0,
  - updateInterval: 128 / sampleRate,
  + updateInterval: channels instanceof OfflineAudioContext ?
  + 128 / channels.sampleRate : 128 / sampleRate,
  });
  - this._duration = duration;
  + this._duration = channels instanceof OfflineAudioContext ?
  + channels.length / channels.sampleRate : duration;
  }
  /**
  