GitHub.MarkDeletedFiles.js

(function selectUnimportant() {
    let files = document.querySelectorAll('.file');
    for (let index = 0; index < files.length; ++index) {
        let content = files[index].innerHTML;
        if (content.indexOf('This file was deleted') !== -1 || content.indexOf('No changes.') !== -1) {
           let checkbox = files[index].querySelector('.js-reviewed-checkbox');
           if (!checkbox.checked) {
              setTimeout(function() {checkbox.click(); }, 666);
           }
        }
    }
})();