chromium/third_party/blink/web_tests/svg/custom/fill-url-percent-encoding.html

<!DOCTYPE html>
<svg>
  <defs>
    <linearGradient id="foo">
      <stop stop-color="green"/>
    </linearGradient>
  </defs>
  <rect width="100" height="100" fill="url(#%66%6f%6f) red"/>
</svg>