function CallbackQueue(arg) {
	    _classCallCheck(this, CallbackQueue);

	    this._callbacks = null;
	    this._contexts = null;
	    this._arg = arg;
	  }
A specialized pseudo-event module to help keep track of components waiting to
be notified when their DOM representations are available for use.

This implements `PooledClass`, so you should never need to instantiate this.
Instead, use `CallbackQueue.getPooled()`.

@class ReactMountReady
@implements PooledClass
@internal