Revert r33630 and do something more sensible.

Revert r33630 and do something more sensible.

I don't think this fixes the underlying problem, but I think that
problem is very extensive. Fixing it would involve a re-thinking of
where and how we call updateBuffer()---the old updateLabels().

This fix also reveals another problem with the TOC, again due to the
early call of on_typeCO_currentIndexChanged(). But that problem is a
slightly different one, I think.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@33680 a592a061-630c-0410-9148-cb99ea01b6c8