chromium/src/third_party/blink/web_tests/fast/canvas/canvas-filter-shadow.html

<canvas id="canvas" width="100" height="100"></canvas>
<script>
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
ctx.fillStyle = '#0f0';
ctx.filter = 'drop-shadow(0px 10px black)';
ctx.shadowOffsetX = 10;
ctx.shadowColor = '#ccc';
ctx.fillRect(20, 25, 50, 40);
</script>