Follow-up of #7107 (#7107 (comment))

Closes #7673

Auditors:

Test Plan:
1. Visit http://jsbin.com/fiyojusahu/edit?html,output
2. In the `output` area, click the `Click me to test an alert` button
3. Make sure the buttons are aligned to the right
4. Visit http://jsbin.com/sadunogefu/edit?html,output
5. In the `output` area, click the `Click me to test a confirm` button
6. Make sure the buttons are aligned to the right