allow `|async` AsyncPipe to work before rendering

[PatrickJS]

make sure |async works

[PatrickJS]

this was fixed after creating checkStable rather than ngZone.onStable

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}