This test passes if it doesn't crash.
<svg width="100" height="100">
<style>
circle::before { content: "foo" }
circle::after { content: "bar" }
</style>
<defs>
<g id="c">
<circle cx="50" cy="50" r="40" stroke="green" stroke-width="4" fill="yellow" />
</g>
</defs>
<use xlink:href="#c"/>
</svg>