chromium/src/third_party/blink/web_tests/svg/custom/mask-with-default-value.svg

<svg xmlns="http://www.w3.org/2000/svg">
<defs>
<mask id="m1">
<rect x="0%" y="0%" width="100%" height="100%"/>
</mask>
</defs>
<rect x="0" y="0" width="120" height="120" fill="green"/>
<rect x="10" y="10" width="100" height="100" fill="red" mask="url(#m1)" />
</svg>