Enable linting for ES6 files
What does this MR do?
Add .js.es6 to file extensions checked by ESLint.
What are the relevant issue numbers?
Follows !5445 (merged)
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Add .js.es6 to file extensions checked by ESLint.
Follows !5445 (merged)