third_party/blink/web_tests/editing/inserting/5002441.html

<p>This tests for a bug where spaces couldn't be inserted before signatures and replies.</p>
<div id="div" contenteditable="true"><br><div>There should be a single space in the paragraph above.</div></div>
<script>
var div = document.getElementById("div");
var selection = window.getSelection();
selection.collapse(div, 0);
document.execCommand("InsertText", false, " ");
</script>