effect-reference-source-alpha-002.html

<!DOCTYPE html>
<html>
<title>CSS Filters: feColorMatrix with SourceAlpha</title>
<link rel="author" title="Stephen White" href="mailto:[email protected]">
<link rel="help" href="https://drafts.fxtf.org/filter-effects-1/#feColorMatrixElement">
<link rel="help" href="https://drafts.fxtf.org/filter-effects-1/#attr-valuedef-in-sourcealpha">
<link rel="help" href="https://crbug.com/331362">
<link rel="match" href="reference/effect-reference-source-alpha-002-ref.html">
<meta name="assert" content="Check that the result of an identity feColorMatrix with SourceAlpha from an element with will-change: transform as input is opaque black"/>

<style>
.rect {
    position: absolute;
    background-color: red;
    width: 100px;
    height: 100px;
    filter: url(#alpha);
    will-change: transform;
}
</style>
<div class="rect"></div>
<svg xmlns="http://www.w3.org/2000/svg" width="0" height="0" version="1.1">
  <defs>
    <filter id="alpha" color-interpolation-filters="sRGB">
      <feColorMatrix in="SourceAlpha"/>
    </filter>
  </defs>
</svg>

chromium/third_party/blink/web_tests/external/wpt/css/filter-effects/effect-reference-source-alpha-002.html