php文件自动在每一行中添加换行符和空格？

I'm working on a wordpress site and I'm editing the function.php. The problem is whenever I made some changes to it and upload back to the server it automatically add an empty line to it.

Original php:

function registerWidget() {
register_sidebar(array(
    'name'          => 'FooterMessage',
    'id'            => 'footer-message',
    'before_widget' => '<div class="FooterMessage">',
    'after_widget'  => '</div>',
));

Few days after and downloaded back from the server:

function registerWidget() {

register_sidebar(array(

    'name'          => 'FooterMessage',

    'id'            => 'footer-message',

    'before_widget' => '<div class="FooterMessage">',

    'after_widget'  => '</div>',

));

Is there a way to prevent this and is there any online tool that allow me to remove all these excessive empty lines without doing it manually?