rerendering bold+plaintext+bold markers causes error: "Failed to execute 'replaceChild' on ‘Node’"

[bantic]

To reproduce:

• type 3 characters of bold text: bab
• select middle character and un-bold it (using cmd-B or "bold" button): bab
• re-bold the middle character -> Uncaught NotFoundError: Failed to execute 'replaceChild' on 'Node': The node to be replaced is not a child of this node.

The error comes from the editor-dom's attempt to reattach the rendered markup section.