QtDeclarative backport request

[Nicolas Fella]

Hi,

to fix https://bugs.kde.org/show_bug.cgi?id=508377 / 
https://qt-project.atlassian.net/browse/QTBUG-149607 please backport 
https://codereview.qt-project.org/c/qt/qtdeclarative/+/768697

It might be too late for the upstream 6.11.3 released, but it's rather 
important to fix regardless.

Cheers

Nico