<!DOCTYPE html>
<body>
    <script>
        if (window.testRunner)
            testRunner.dumpAsText();
        document.designMode = "on";
        document.body.innerHTML = `<div>ANCHOR</div><div><button>FOCUS</button></div>TEXT_AFTER`
        const anchorNode = document.body.firstElementChild.firstChild;
        const anchorOffset = 0;
        const focusNode = document.getElementsByTagName("button")[0].lastChild;
        const focusOffset = focusNode.textContent.length;
        getSelection().setBaseAndExtent(anchorNode, anchorOffset, focusNode, focusOffset);
        getSelection().getRangeAt(0).deleteContents();
        document.execCommand('FontSizeDelta', false, '1px');
        document.body.textContent = 'The test PASS if it does not crash.';
    </script>
</body>