fix typo (#8760)

It seems that the class name in comments should be CallbackQueue

src/renderers/shared/stack/reconciler/CallbackQueue.js

@@ -23,7 +23,7 @@ var invariant = require('invariant');
  * This implements `PooledClass`, so you should never need to instantiate this.
  * Instead, use `CallbackQueue.getPooled()`.
  *
- * @class ReactMountReady
+ * @class CallbackQueue
  * @implements PooledClass
  * @internal
  */