Support reverse scrolling in iOS Safari

[inokawa]

close #43

This PR will change jump compensation behavior in iOS WebKit browsers.

[oleggrishechkin]

Hi, @inokawa. Sorry for writing in this closed PR, but did you find any pretty solution to fix iso safari scrolling?
In my library (also virtualization) I'm using negative or positive margin-top hack to make scroll compansation on new item render/item size change.

Oh... why ios safari uses this awful technic and nobody fixed this at the end of 2023...

[inokawa]

Yes, it's very sad behavior in iOS Safari... My approach is not perfect but doing my best.

As you probably know, we can't change scroll position in iOS Safari during momentum scrolling or touching so I compensate it with adding offset to top(similar to margin).
I want to revert it and fix scroll position after a while. However I couldn't find reliable way to know when Safari started accepting scroll position change. In such timing that may be ok or may not be ok,
a workaround like https://github.com/prud/ios-overflow-scroll-to-top is used.

[oleggrishechkin]

Yes, it's very sad behavior in iOS Safari... My approach is not perfect but doing my best.

As you probably know, we can't change scroll position in iOS Safari during momentum scrolling or touching so I compensate it with adding offset to top(similar to margin).

I want to revert it and fix scroll position after a while. However I couldn't find reliable way to know when Safari started accepting scroll position change. In such timing that may be ok or may not be ok,

a workaround like https://github.com/prud/ios-overflow-scroll-to-top is used.

Thank you. Nice emulation of smooth/momentum scrolling. It may help me with my research and tests.