Terminate download when X button is pressed

[teikjun]

Outline of Solution

• Modify the behavior of X button to terminate the download

Remarks
Below is a record of the thought process, in case anyone revisits this part of the code.

• Originally, X button does not terminate the download. The rationale was:

1. If the user intentionally wants to close the modal to view other parts of the page while waiting, they can do so by intentionally hitting the X button.
2. To avoid having two different looking UI components display the same behavior (Intuitively, things that look different should do different things)

• Rationale for the change is to prevent weird UI interactions that may occur as a result of users messing around with UI during the download

[teikjun]

@moziliar Feel free to merge this if it looks fine! :)

[moziliar]

LGTM