I am very happy this works on FF57, thank you!
However, I am facing a small issue. When I create a new tab then the desired page, as modified with this addon, appears. On the other hand, when I open the page about:newtab then the default firefox newtab page opens like if I did not have this addon installed. What is the page I should set to the browser.startup.homepage in about:config in order to open the modified newtab page as per this addon when I press the home button?