Tests for createlink bugs

Inserting link currently *fails* reliably on `BROWSER_NAME='firefox' BROWSER_VERSION='29' PLATFORM='WINDOWS' ` 
It looks as if `range.setStartAfter` also sets a matching end container and offset. This isn't documented. The only spec for Range (2000) I could find is here, which doesn't specify what should happen in this instance: http://www.w3.org/TR/2000/REC-DOM-Level-2-Traversal-Range-20001113/ranges.html

If it’s something that just happens to be implemented in both Chrome and Firefox, we should probably stick with the spec and use `setStartAfter` *and* `setEndAfter`.