function unwrap(selectedNode) {
      var parentElement = dom.getParentElement(selectedNode, { nodeName: ["P", "DIV"] }, 2);
      if (!parentElement) {
        return;
      }

      var invisibleSpace = document.createTextNode(wysihtml5.INVISIBLE_SPACE);
      dom.insert(invisibleSpace).before(parentElement);
      dom.replaceWithChildNodes(parentElement);
      composer.selection.selectNode(invisibleSpace);
    }
Some browsers don't insert line breaks when hitting return in a contentEditable element
   - Opera & IE insert new <p> on return
   - Chrome & Safari insert new <div> on return
   - Firefox inserts <br> on return (yippie!)

@param {Element} element

@example
   wysihtml5.quirks.insertLineBreakOnReturn(element);