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chromium/third_party/blink/web_tests/compositing/overflow/clip-rotate-opacity-fixed.html 

<!DOCTYPE html>
Passes if no red.
<div style="width: 300px; height: 300px; background: green; outline: 1px solid green; position: absolute; z-index: 1"></div>
<div style="width: 300px; height: 300px; overflow: hidden">
  <div style="transform: rotate(45deg); width: 300px; height: 300px">
    <div style="opacity: 0.9">
      <div style="position: fixed; will-change: transform; width: 300px; height: 300px; background: red"></div>
    </div>
  </div>
</div>