bug#4835: 23.1; Improper `Invalid face reference' messages. Performance degraded.

[Drew Adams]

> > We should make the right fix, not the easiest one based on our not
> > being sure what the code does or why.
> 
> It's pretty clear, from the doc string plus the various parts of
> font-lock code that assume function names, that the code was not
> intended to work with lambda expressions.  It would be nice 
> if it worked with lambda expressions, but that would be a new
> feature, not a bug fix.

Nonsense. You could say that it's crystal clear from the Elisp manual that
_function_ was meant (since that's what is says) and not symbol function or
"function name" (which would be a string). The code is bugged wrt its mission as
documented in the manual, which is the closest thing we have to a spec.

Kidding aside, this is a chance to DTRT, not just sidestep the problem because
the code might be unclear or it takes some studying to understand it.

At any rate, as I said, the bug (`Invalid face reference' messages and the
attendant slowdown) seems to be there even when I use a symbol function. Unless
I'm doing something wrong (which is why I asked for help).