Fix item positioning with multiple removes before the visible area.
Fix item positioning with multiple removes before the visible area.

The index of the previous first visible item needs to be adjusted
when items are removed before it in order to comparable against
later changes.

Change-Id: I3c72abb4dfc9c2ccc9b299dda186ecdc3994a735
Reviewed-by: Bea Lam <3b8b412f85e38e2fbf2a7d737c89d787c51aca40@nokia.com>

matthewvogt/qtdeclarative,crobertd/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,jfaust/qtdeclarative,matthewvogt/qtdeclarative,corngood/qtdeclarative,qmlc/qtdeclarative,crobertd/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,crobertd/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,crobertd/qtdeclarative,crobertd/qtdeclarative,corngood/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,matthewvogt/qtdeclarative,corngood/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,corngood/qtdeclarative,jfaust/qtdeclarative,corngood/qtdeclarative,corngood/qtdeclarative,jfaust/qtdeclarative,jfaust/qtdeclarative,corngood/qtdeclarative,jfaust/qtdeclarative,jfaust/qtdeclarative,crobertd/qtdeclarative,jfaust/qtdeclarative,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,crobertd/qtdeclarative