When item.height > viewport.height, the next item is not found
correctly, resulting in an infinite loop.
In this case, move directly to the next item.
Pick-to: 6.4 6.3 6.2
Change-Id: I67a40a079ca9dd9189bf84ae550758c685b83d75
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>