animated-reference-in-shadow-tree.html

<!DOCTYPE html>
<svg style="display:none;">
    <rect id="rectReference" width="10" height="10" fill="red" />
</svg>
<template id="template">
   <svg width="200" height="200">
        <rect id="rectReference" width="100" height="1" fill="green">
            <set xlink:href="#rectReference" attributeName="height" to="100"/>
        </rect>
   </svg>
</template>
<script>
    document.body.attachShadow({mode: 'open'}).appendChild(template.content.cloneNode(true));
    if (window.testRunner) {
        testRunner.waitUntilDone();
        window.requestAnimationFrame(function() {
            testRunner.notifyDone();
       });
    }
</script>

chromium/third_party/blink/web_tests/svg/dom/animated-reference-in-shadow-tree.html