Don't suggest saving empty files on closing them

If I erase everything I typed in Scratch without saving the file anywhere, and then close the tab, Scratch still prompts if the file should be saved. I often press Ctrl+A and Backspace to get rid of something and indicate I don't want it saved; the prompt is rather intrusive in that case.

Since it makes no sense to save empty files (unless explicitly requested with the Save button), Scratch should not prompt if they should be saved on closing a tab with no text in it.

This should be like that only in save-as-you-type mode; in case of manual saving that's a valid modification that still should be manually saved or discarded.