MultimediaViewer currently does not have any browser tests.

It would be good to have tests for the core functionality to prevent bugs like T379835 from getting into production environments in the future.

Some things that could be tested:

• Clicking on an image should open MMV and update the URL accordingly.
• Closing an image using either ESC or the Close button should return back to the page view and update the URL accordingly.
• Clicking the next/prev image buttons should change the displayed image and update the URL accordingly.