Image not Recognized by JavaScript

HTML Code

<div>
    <img  id="in" width="300px">
</div>

JavaScript Code

    var image = document.getElementById("in");
image.src = "http://ift.tt/1BfFSww";
image.animate({marginTop: "100vh"});

Everytime I run this program, I am able to load the image, but I am unable to perform the animation on it. I get this error:

Uncaught TypeError: Failed to execute 'animate' on 'Element': No function was found that matched the signature provided.

What should I do to fix this?

Fiddle

Thanks in advance!