Fix 12966. A few notes:
* we need to consider both regular insets and argument insets.
* in passthru layouts (such as verbatim) parentheses still need
to be reversed.
* all arguments of type 'listpreamble' are passthru (this isn't a rule,
this is just what happen in practice).
* custom layout and insets from the local layout, or a custom module
are not considered.
Signed-off-by: Udi-Fogiel <udifoglle@gmail.com>
ca2c9d8b46