message: clean up time value on dispose
diff: @@ -85,6 +85,7 @@ define(["Tone/core/Tone", "Tone/type/Ticks"], function(Tone){
  Tone.prototype.dispose.call(this);
  this.Transport = null;
  this.callback = null;
  + this.time = null;
  return this;
  };
  