Add Safari versions for XMLSerializer API (#8642)
Add Safari versions for XMLSerializer API (#8642)

This PR adds real values for Safari (Desktop and iOS/iPadOS) for the `XMLSerializer` API, based upon manual testing.

Test Code Used: `'XMLSerializer' in self`
mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data