[TableView, TreeTableView] in single cell and multiple selection mode, Shift+PageUp/PageDown doesn't scroll the tableview.

It happens with 8 and 8u20.

For TableView and TreeTableView, in single cell and multiple selection mode, There are 2 problems with Shift+PageUp/PageDown:
1. select a cell, then press Shift+PageUp/PageDown for several times. The TableView/TreeTableView doesn't scroll to previous/next pages to select more cells. This doesn't happen with row selection mode.
2. on the first screen, select a cell, then press Shift+PageUp twice, all selected cells are unselected. But they should keep selected if it reaches top of the tableview.