third_party/blink/web_tests/svg/custom/viewport-update.svg

<svg xmlns="http://www.w3.org/2000/svg" viewBox="-100 -100 800 600">
<script>
document.documentElement.setAttribute("viewBox", "0 0 800 600");
</script>
<rect x="-100" y="-100" width="100" height="100" fill="red"/>
<rect x="0" y="0" width="100" height="100" fill="green"/>
</svg>