Quiz grades report delete selected attempts conformation focuses on cancel

Issue
Form validation cues - The confirmation alertBox that pops up when the user clicks the delete selected attempts button has direct focus on the "Cancel" button instead of reading through the alert dialog first which makes it difficult for a screen reader user to understand the context.

Standard Level*
WCAG 2 3.3.1 (A) http://www.w3.org/WAI/WCAG20/quickref/#qr-minimize-error-identified

Impact
Critical

Example Link
http://demo.moodle.net/mod/quiz/report.php?id=2461&mode=overview

Test Steps

1. Login as a student
2. navigate to course
3. Click on quiz
4. Click Edit quiz
5. Click the attempts link
6. Select attempts
7. Click the delete selected attempts
8. Notice that the confirmation modal starts the user on cancel.