JIRA overrides browser shortcuts when user is on an Agile Board

Issue Summary

When a user switch between tabs in Firefox on linux using the Alt +1 to Alt + 9 and you have an Agile board open, instead of switching the browser tabs, JIRA overwrites this behavior registering the event as if you only pressed the number for example, if you press Alt + 1 JIRA registers this as just 1 and this would trigger the shortcut to access backlog.

Steps to reproduce

1. Open JIRA in a Firefox browser.
2. Access an Agile project.
3. Press the switch tab controls as described Alt + 1-9

Expected Behavior

JIRA would switch to a new tab as was expected.

Actual Behavior

JIRA overwrites the expected browser behavior and instead notices just the number keys hence triggering JIRA's own shortcuts instead.