bookmarklet

javascript:(function()%7B%24(%22.file%20.meta%22).each(function()%7Bvar%20btn%3D%24(%22%3Cbutton%20/%3E%22,%7Bclass:%22fileHider%22,text:%22HIDE%22%7D)%3B%24(this).append(btn)%3B%7D)%3B%24(%22.fileHider%22).on(%22click%22,function()%7Bvar%20data%3D%24(this).parents(%22.file%22).find(%22.data,%20.image%22)%3Bdata.toggle()%3B%7D)%3B%7D)()%3B

gh-pr-helper.js

(function() {
    $(".file .meta").each(function() {
        var btn = $("<button />", { class: "fileHider", text: "HIDE" });
        $(this).append(btn);
    })

    $(".fileHider").on("click", function() {
        var data = $(this).parents(".file").find(".data, .image");
        data.toggle();
    })
}());