[V3dot10] Font problems

[Ralph Johnson]

I've been having trouble running the tests for the last few weeks.
The image goes into an infinite loop and then crashes.  Whenever I
have been able to figure out why, it is always due to the TrueType
fonts.  In particular, sometime a TTCFont has itsself as its
"fallbackFont", and then methods like #ascent go into an infinite
loop.  I have solved that problem by redefining #fallbackFont: to
check for recursion.  This makes things work better, but I am still
getting a crash in FontTest.  Hoewver, when I try to isolate it, it
won't appear.

The bug is frustrating because sometimes the tests work, and sometimes
they crash the image.  In general, if they work the first time then
they will not work the second time.  I have noticed that running the
tests changes the fonts used by the browser and other tools.  So, it
makes sense that running the tests twice will have a different result
if the tests depend on the environment in some way.

I'm going to keep on working on this, but if I can't find out what is
causing the problems then we are going to backout all the changes to
fonts and see if that works better.  That would be too bad, because
the new fonts are much better looking than the old ones.  But
reliability is more important.  So, any help would be appreciated!

Recently I've been working with Edgar's latest 7105 image at
http://ftp.squeak.org/3.10alpha/

-Ralph