Fix content pos adjustment when resizing first item

Fix content pos adjustment when resizing first item

If visibleItems.first() changes size in a ListView, the size change
should be made in the direction of the content flow. This was not
working correctly for layouts other than the default vertical+LTR
layout. This patch fixes the issue for other layouts and also fixes
resizing of implicitly sized delegates (e.g. positioners) within the
default layout.

Change-Id: Ib1d84ce000a3a341fe617cf644420dc5d589d577
Reviewed-by: Andrew den Exter <andrew.den-exter@nokia.com>