QAbstractItemModelTester: Check size hint role

Returning the wrong data type for Qt::SizeHintRole may lead to a size
of 0,0 and the item disappearing.

Task-number: PYSIDE-2772
Change-Id: I906445f2ed2141da2606774f2b8ad6282662eb17
Reviewed-by: hjk <hjk@qt.io>
(cherry picked from commit 84f2cd6523081ed8774b2a9fe9ee36d05172ff50)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/testlib/qabstractitemmodeltester.cpp

@@ -669,6 +669,10 @@ void QAbstractItemModelTesterPrivate::data()
                 || state == Qt::Checked);
     }
 
+    QVariant sizeHintVariant = model->data(model->index(0, 0), Qt::SizeHintRole);
+    if (sizeHintVariant.isValid())
+        MODELTESTER_VERIFY(sizeHintVariant.canConvert<QSize>());
+
     Q_Q(QAbstractItemModelTester);
 
     if (!QTestPrivate::testDataGuiRoles(q))