ANG-12114: fix index of pages update rountine in VerticalDelegate.js

## Issue
Index of pages in DataList have a same value in certain case.

## Cause
refresh() function has a index setting routine according to pageCount value.
But they can not handle a condition like blew.

(firstIndex > pageCount && secondIndex > pageCount) ==> OK
(firstIndex > pageCount && secondIndex < pageCount) ==> OK
(firstIndex < pageCount && secondIndex > pageCount) ==> Not Good(result : firstIndex == secondIndex)
(firstIndex < pageCount && secondIndex < pageCount) ==> OK

## Fix
Add one line which can handle that condition.