typing in link causes console error

[bantic]

On Mac, Chrome:
Select some text, use the toolbar to create a link, and then type text in the link. Causes console error: "Cannot read property 'parentNode' of undefined".

This appears to be due to the fact that, although we reparse after the link command calls document.execCommand('createLink'), we don't rerender the new markers. They end up in the Abstract Tree but their rendered elements are not in the element map, so the next time we type -> reparse -> rerender, we cannot tear down those markers.