IsPredefined.
The point of this is that the current tag is doing both of these jobs,
and they are different. The achemso class shows this, since it uses
float.sty to define three different kinds of floats internally. We have
to set NeedsFloatPkg to false to prevent LyX from trying to redefine
them, but then we complain that there is no list command defined and so
do not enter it in Insert>List/TOC.
The new tag is not yet functional, just there.
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@37430 a592a061-630c-0410-9148-cb99ea01b6c8
4c95238626