LayoutTests/fast/images/cached-clipped-pdf.html

<style>
    img {
        width: 200px;
        height: 200px;
    }
</style>
<img src="resources/green_rectangle.pdf">
<script>
    if (window.testRunner && window.internals)
        window.internals.settings.setPDFImageCachingPolicy("clipBoundsOnly");
</script>