If maxChildSize is set to 1.0 and actual fractional value of the parent is less than 1.0 (child can't fill parent completly), then once DraggableScrollableSheet reaches its max it won't scroll back down.

Steps to Reproduce

1. Create a DraggableScrollableSheet with maxChildSize set to 1.0
2. Set the parent containers actual fractional value to less than 1.0
3. Run app and scroll the sheet to its highest position. (it will get stuck)

https://gist.github.com/mrmko/40e34852fff8686753e0e9b8b5234784

@dnfield