Amends ca15f650a1, after which scrolling
right to fill any gap might have resulted in overshooting to a negative
scrollOffset.
When we scroll right to fit the current tab, then we never want to end
up with a negative scroll, so clamp the result accordingly.
Augment test case accordingly. Since some styles align the tab bar in
the center, replace the calculation of the scroll offset with access to
the private data member (which inverts the sign when compared to the
calculated value).
Task-number: QTBUG-113140
Fixes: QTBUG-113376
Pick-to: 6.5 6.5.1
Change-Id: Ibdc6686b9dbd41b1ae3560e2227fa121d9b20e18
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
2434573f5e