message: using clockSource API
diff: @@ -42,6 +42,7 @@ define(["Tone/core/Tone", "Tone/core/Context"], function (Tone) {
  */
  this._currentTime = 0;
  + this.clockSource = "offline";
  //modify the lookAhead and updateInterval to one block
  this.lookAhead = 0;
  this.updateInterval = this.blockTime;
  @@ -57,17 +58,6 @@ define(["Tone/core/Tone", "Tone/core/Context"], function (Tone) {
  return this._currentTime;
  };
  - /**
  - * Overwrite this method since the worker is not necessary for the offline context
  - * @private
  - */
  - Tone.OfflineContext.prototype._createWorker = function(){
  - //dummy worker that does nothing
  - return {
  - postMessage : function(){}
  - };
  - };
  -
  /**
  * Render the output of the OfflineContext
  * @return {Promise}
  