abce89d1bc
Motivation: Revert d0943dcd30b08eb4043aeb88fd983bcebf8c3432. Delaying the notification of writability change may lead to notification being missed. This is a ABA type of concurrency problem. Modifications: - Revert d0943dcd30b08eb4043aeb88fd983bcebf8c3432. Result: channelWritabilityChange will be called on every change, and will not be suppressed due to ABA scenario.