Revert mark idle (#31487)
Revert mark idle (#31487)

* Turn off mark_when_idle option as it appears to cause a regression.
We can turn it back on once we investigate the cause and fix it.

* Format.
chinmaygarde/flutter_engine,jason-simmons/flutter_engine,jason-simmons/flutter_engine,jason-simmons/flutter_engine,chinmaygarde/flutter_engine,devoncarew/engine,flutter/engine,flutter/engine,rmacnak-google/engine,devoncarew/engine,jason-simmons/flutter_engine,rmacnak-google/engine,rmacnak-google/engine,devoncarew/engine,chinmaygarde/flutter_engine,flutter/engine,jason-simmons/flutter_engine,flutter/engine,jason-simmons/flutter_engine,devoncarew/engine,flutter/engine,rmacnak-google/engine,devoncarew/engine,chinmaygarde/flutter_engine,jason-simmons/flutter_engine,flutter/engine,devoncarew/engine,chinmaygarde/flutter_engine,chinmaygarde/flutter_engine,rmacnak-google/engine,flutter/engine,flutter/engine,rmacnak-google/engine,jason-simmons/flutter_engine,rmacnak-google/engine,devoncarew/engine,chinmaygarde/flutter_engine