Do not set any textContent in overlay highlight spans. The reason for this change is that selection behaves weirdly when there's an absolutely positioned span with text content.
Created attachment 185750 [details] Patch
Comment on attachment 185750 [details] Patch Clearing flags on attachment: 185750 Committed r141414: <http://trac.webkit.org/changeset/141414>
All reviewed patches have been landed. Closing bug.