When cloning a QTextDocument, the text fragment of the original document
is copied into the new one, which results into copying also the
formatting attributes. However, when the text document is empty, the
corresponding text fragment is also empty, so nothing is copied.
If we want to transfer the formatting attributes for an empty document,
we need to set them explicitly.
Fixes: QTBUG-80399
Change-Id: I382cd0821723436120af47c06ec7bfa849636307
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
81459dd9c0