ScrollablePositionedList: make itemCount optional

[tarobins]

[anaurelian]

In the meantime, does using a very large itemCount have any side effects? Is there any extra memory allocated, will it slow down the app, etc.?

ScrollablePositionedList.builder(
  itemCount: 1000000000,

[tarobins]

should be fine

[jangruenwaldt]

I think it's a good feature for calendars. Would be nice to have. But the 10K index workaround works for me.