485f642047
Motivation: Revert 2e68e370253d06e78e3970b7be77216d6f1f6b85. Delaying the notification of writability change may lead to notification being missed. This is a ABA type of concurrency problem. Modifications: Revert 2e68e370253d06e78e3970b7be77216d6f1f6b85. Result: channelWritabilityChange will be called on every change, and will not be suppressed due to ABA scenario.