WebkitUserSelects will resolve to user-select but not to -webkit-user-select

[respigen]

Background:
user-select is supported without a prefix in most but not all major browsers. Previously this required a -webkit vendor prefix.

Functionally for the supporting browsers -webkit-user-select is the same as user-select and user-select is preferred. When using WebkitUserSelect, it is resolved to user-select, which is usually fine.

Problem:
Safari (as at time of writing) does not support user-select without a prefix. When I write the VendorLonghandProperties to specifically mean -webkit, I intend it to mean -webkit-user-select and not user-select

https://developer.mozilla.org/en-US/docs/Web/CSS/user-select

I don't actually think it's something that can be solved helpfully and it does not seem to be the responsibility of this package to solve.
I figured I'd open this for someone else to read if they run into similar issues because it took me a while to understand why this wasn't working for Safari.