This reverts commit 7257862fb2.
It has been reported that this patch causes widgets with certain effects
become invisible.
Task-number: QTBUG-60231
Task-number: QTBUG-66803
Task-number: QTBUG-66387
Change-Id: I9c3c4cf2f17ac639d1aee5489b665aa1e165af16
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>