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chromium/third_party/blink/web_tests/paint/invalidation/window-resize/window-resize-background-image-fixed-generated.html 

<!DOCTYPE html>
<script src="../../../resources/run-after-layout-and-paint.js"></script>
<script src="../resources/window-resize-repaint.js"></script>
<style>
body {
    background-image: linear-gradient(red, blue);
    background-attachment: fixed;
}
</style>