Privacy Browser Android

This would involve updating WebView's internal scroll tracker whenever `startNestedScroll()` is called.

https://developer.android.com/reference/androidx/core/view/NestedScrollingChild#startNestedScroll(int)

And would fix the buggy behavior described at https://www.stoutner.com/bug-in-webviews-handling-of-nested-scrolling/.

I would only make this change if it isn't too invasive and would be easy to maintain in the long run.