chromium/third_party/blink/web_tests/editing/selection/iframe-select-expected.html

<!DOCTYPE html>
<img src="../../css2.1/support/1x1-transparent.png" id="target" style="width: 100px; height: 100px; position: absolute; top: 50px; left: 50px"/>
<script>
    var selection = getSelection();

    selection.setBaseAndExtent(document.querySelector("#target"), 0, document.querySelector("#target"), 1);
</script>