Status of AudioWorkerNode in Web Audio API

According to the docs, the AudioWorker node should be functional. When I try to create it, the console throws back:

TypeError: context.createAudioWorker is not a function.

My code:

var context;
if (typeof AudioContext !== 'undefined') {
  context = new AudioContext();
} 
else if (typeof webkitAudioContext !== 'undefined') {
  context = new webkitAudioContext();
} 
else {
  throw new Error('AudioContext not supported. :(');
}

var foo = context.createAudioWorker();

Am I doing this wrong, or has it not been implemented in FF/Chrome?

It has not been implemented yet in Chrome. It's in the plan, but implementation has not yet started.