9a263466ae
#### (plus some more docs) Fixes https://github.com/flutter/flutter/issues/76760 Fixes https://github.com/flutter/flutter/issues/82391 Fixes https://github.com/flutter/flutter/issues/45619 Fixes #117316 Fixes #110956 Fixes #127282 Fixes #32563 Fixes #46089 Fixes #79077 Part of fixing #62833 This fixes (a bunch of) issues that have been reported differently over the years, but all have the same root cause. Sometimes the NestedScrollView would incorrectly calculate whether or not there is enough content to allow scrolling. This would only apply to drag scrolling (not mouse wheel scrolling for example). This did not relate to how the extent of the NestedScrollView is computed, but just the logic that enabled the actual drag gestures. This fixes that. :)