Chrome getBBox fail

HTML

<div id="output"></div>

<svg>
<path id="test" d="M30 30L50 50" stroke-width="3" stroke="black"></path>
</svg>

JavaScript

var path = document.getElementById('test');
var output = document.getElementById('output');


output.innerHTML += (path.getBBox().x + " " + path.getBBox().y) + "<br>";

path.setAttribute('d', "M80 80L100 100");

output.innerHTML += path.getBBox() + " " + path.getBBox().y;
console.log(path.getBBox());