In QGraphicsScene's function draw, don't copy the children into a
const copy (to prevent detaching in the loops), as they might get
sorted. Instead, use a const reference.
Amends e349f787d5, which introduced
the bug by making a copy of the unsorted list.
Fixes: QTBUG-81316
Pick-to: 6.0 6.1
Change-Id: Iab9b87e75178a883806088a9db234c7a2aaa9301
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
269fdef53d