Add Firefox versions for api.Document.documentURI.readonly (#12269)
Add Firefox versions for api.Document.documentURI.readonly (#12269)

This PR adds real values for Firefox and Firefox Android for the `documentURI.readonly` member of the `Document` API, based upon results from the [mdn-bcd-collector](https://mdn-bcd-collector.appspot.com) project (v3.2.12).

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