chromium/third_party/blink/web_tests/svg/custom/attribute-namespace-check.svg

<svg xmlns='http://www.w3.org/2000/svg' xmlns:bogus='http://www.example.com' width='100px' height='100px'>
  <g fill='green'>
    <rect width='100' height='100' bogus:fill='red' />
  </g>
</svg>