(v6.x backport) test: use ES6 classes instead of util.inherits
Backport of https://github.com/nodejs/node/pull/16938 to v6.x.
Thanks to @MylesBorins for landing backport PRs required for this to land cleanly!
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Backport of https://github.com/nodejs/node/pull/16938 to v6.x.
Thanks to @MylesBorins for landing backport PRs required for this to land cleanly!