The WebAudio spec (https://webaudio.github.io/web-audio-api/#AudioScheduledSourceNode) says AudioBufferSourceNode has its own stop method, instead of inheriting from AudioScheduledSourceNode:

[Exposed=Window]
interface AudioScheduledSourceNode : AudioNode {
  attribute EventHandler onended;
  void start(optional double when = 0);
  void stop(optional double when = 0);
};

Chrome's implementation doesn't do this.  Make it match.

(I think the spec should be changed, but that seems very unlikely at this point.)