testSelectionPreservingNormalize2() {
    const parent = $('normalizeTest-3');
    const def = $('def-3');
    const jkl = $('jkl-3');
    def.firstChild.splitText(1);
    jkl.firstChild.splitText(2);

    Range.clearSelection(window);
    editorRange.selectionPreservingNormalize(parent);

    // Check that everything was normalized ok.
    assertEquals(1, def.childNodes.length);
    assertEquals(1, jkl.childNodes.length);
    assertFalse(Range.hasSelection(window));
  }
Make sure that selectionPreservingNormalize doesn't explode with no
selection in the document.