Check if we are handling data-urls the way we expect

[johnshaughnessy]

When we encounter a data: url, we execute a regex, but seem to throw away the result. Did we intend to return or use this term, matches[1] at this line? https://github.com/mozilla/hubs/blob/fd28c27f7d23b9d69c0ffa5dbcc1f0a5dcbfb5ad/src/utils/media-url-utils.js#L130