This PR does two things:
1. Remove an unneeded mootools modal call
2. Restores the functionality on the buttons inside the modal
Testing
Apply this PR
Goto administrator/index.php?option=com_banners&view=tracks
Observe that no mootools are loaded
Press the button export on the toolbar (top right)
press the Export button
repeat and press the cancel button
Everything should be fine!
This was corrected elsewhere