Merge branch 'MDL-60427_dnd_folder_improved' of git://github.com/davo…

…smith/moodle

course/dndupload.js

@@ -818,7 +818,16 @@ M.course_dndupload = {
            resel.parent.removeChild(resel.li);
            new M.core.alert({message: M.util.get_string('filereaderror', 'moodle', file.name)});
        };
        reader.readAsText(file.slice(0, 5)); // Try reading the first few bytes of the file.
        if (file.size > 0) {
            // If this is a non-empty file, try reading the first few bytes.
            // This will trigger reader.onerror() for folders and reader.onload() for ordinary, readable files.
            reader.readAsText(file.slice(0, 5));
        } else {
            // If you call slice() on a 0-byte folder, before calling readAsText, then Firefox triggers reader.onload(),
            // instead of reader.onerror().
            // So, for 0-byte files, just call readAsText on the whole file (and it will trigger load/error functions as expected).
            reader.readAsText(file);
        }
    },

    /**