function ReactMountReady(initialCollection) {
  this._queue = initialCollection || null;
}
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 `ReactMountReady.getPooled()`.

@param {?array<function>} initialCollection
@class ReactMountReady
@implements PooledClass
@internal