Fix the accessibility check for a modal dialog

A modal dialog in your app looks right, but keyboard and screen reader users cannot use it. It closes when you click the overlay, and its close "button" is a span with a click handler. Your team now runs an acceptance check that lists which dialog requirements a modal still misses.

An assistant wrote missing_dialog_requirements(implemented). It is in the editor. It has a bug. Find it and fix it.

Input and output:

• implemented: the names of the things the modal does, as strings. It can be empty, hold duplicates and hold names that are not requirements.
• Return a list of the requirement names the modal does not meet.

Rules the tests check:

• There are exactly eight requirements: "aria-labelledby", "aria-modal", "button-close", "escape-closes", "focus-on-open", "focus-restore", "focus-trap" and "role-dialog".
• A requirement is met only when its exact name is in implemented. Matching is case sensitive.
• No other entry meets any requirement.
• Duplicates change nothing.
• Return the unmet requirements in the order listed above, which is alphabetical. Return an empty list when all eight are met.