Re-implement onWheel to fix inverted scrolling

[danalloway]

Beginning with this issue #995 and then this pull request #1137 with it's review, this is my attempt at a fix for inverted scrolling direction.

The original pull request #1137 did a few things differently and did not work properly on Firefox.

This PR:

• Addresses an issue with Firefox using deltaMode of 1 which gives you the number of lines, not pixels, in the deltaY value of the onWheel event. This results in the inverted scroll only scrolling a few pixels at a time.
• Uses the onWheel prop that is passed to the underlying ScrollView to listen to the wheel event instead of attaching an additional one. This eliminates the need to attach and detach listeners.
• Dispatches the onWheel event to any child lists as well as forwards the onWheel prop on just like how it does in _onScroll (do we want to do this, is this right?)

How I'm figuring out the number of pixels in a line is interesting, it only applies to events that have their deltaMode set to 1 though. I question if we even need this? is just setting it do the default enough for a proper scroll experience?

[danalloway]

testing this a bit more and it appears to have issues on Windows and Android, will update if I find a solution

[danalloway]

there are some cases where the corrected inverted scrolling jumps backwards as you scroll (can easily reproduce in the Brave browser)
wrapping the scrollTop assignment in a setTimeout(() => {}, 0) resolves the issue
can anyone shed some light on why that would happen?

[danalloway]

do we need this preventDefault here?

[danalloway]

ok, it looks like we do, as it breaks the scrolling in Chrome without it

[danalloway]

ok, everything works properly on Windows across Brave, Firefox, Edge and Chrome now.
just need to confirm that scrolling in Chrome on Android works properly

[danalloway]

broken again on latest version of chrome
fixing the scrolling on the scaleY -1 hack with another hack just doesn't smell right

going to close this PR for now, this isn't the way to solve it

[necolas]

Thanks for looking into this. I'll give this some thought as it might be something we can solve at a lower level in the future

[danalloway]

you're welcome, and when that time comes let me know how I can help, even if it's just testing or vetting an idea

[annie-elequin]

Hey y'all, attempting to build a chat web app and running into this same problem with the inverted FlatList. is there a recommended way to workaround the scrollwheel for now, or was it not really solved?