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chromium/third_party/blink/web_tests/images/imagemap-overflowing-polygon-focus-ring.html 

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<p>Assuming the port-specific theme draws focus rings, this test can be used to ensure that a focus ring is drawn for an &lt;area shape=&quot;polygon&quot;&gt; that is overflowing the bounds for the img element. This test PASSED if a clipped star-shaped focus ring is drawn around the &lt;area&gt; in the imagemap (below).</p>
<map name="imagemap">
    <area id="area" shape="polygon" coords="60,-10,0,160,150,40,-30,40,120,160" href="#dummy" />
</map>
<img width="128" height="128" usemap="#imagemap" />
<script>document.getElementById("area").focus()</script>
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