Fix the crashes when animated QTreeWidgetItems are hidden

QTreeView's drawTree implementation performs lazy layouting
when calling itemDecorationAt. If animations are enabled,
this can change the list of items, and invalidate the copy
made earlier.

Don't copy the list of items, use a reference instead so that
code iterating over the items later operates on valid data.

Add an assert in the private itemHeight method, it must not
be called with an index that is out of bounds.

Fixes: QTBUG-42469
Change-Id: Ifdb782881447912e00baffd1c407de10a1d8d0d4
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit f140ef04a0c54c2c8a699db33433b8d7235d137c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

0 files changed, 0 insertions, 0 deletions