Add Firefox versions for XPathResult API (#12887)
Add Firefox versions for XPathResult API (#12887)

This PR adds real values for Firefox and Firefox Android for the `XPathResult` API, based upon results from the [mdn-bcd-collector](https://mdn-bcd-collector.appspot.com) project (v4.0.0).

Tests Used: https://mdn-bcd-collector.appspot.com/tests/api/XPathResult
chrisdavidmills/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data