LayoutTests/editing/mac/input/ime-recomposition-preserves-positioned-block.html

<!DOCTYPE html>
<meta charset="utf-8">
<script src="../../../resources/dump-as-markup.js"></script>
<div id="editor" contenteditable="true"><div id="target" style="position: relative;">日本語</div></div>
<script>
Markup.description("Starting an IME recomposition should preserve the positioned block containing the selected text.");

const target = document.getElementById("target");
getSelection().setBaseAndExtent(target.firstChild, 0, target.firstChild, 3);
Markup.dump("editor", "Before recomposition");

if (window.textInputController) {
    textInputController.setMarkedText("日本語", 0, 3);
    Markup.dump("editor", "During recomposition");
    textInputController.insertText("日本語");
    Markup.dump("editor", "After committing recomposition");
}
</script>