code: function createBookmark(dom, rng) {
          if (rng && rng.startContainer) {
            // Verify that the range is within the root of the editor
            if (!dom.isChildOf(rng.startContainer, dom.getRoot()) || !dom.isChildOf(rng.endContainer, dom.getRoot())) {
              return;
            }
  
            return {
              startContainer: rng.startContainer,
              startOffset: rng.startOffset,
              endContainer: rng.endContainer,
              endOffset: rng.endOffset
            };
          }
  
          return rng;
        }
docs: We can't store a real range on IE 11 since it gets mutated so we need to use a bookmark object TODO: Move this to a separate range utils class since it's it's logic is present in Selection as well.