SyntaxMorph is in the Etoys package, but is missing the asMorphicSyntaxIn:
methods that are needed in the ParseNode hierarchy.

I tried importing the missing methods from an Etoys development image, which
is sufficient to make SyntaxMorph class>>test work. But SyntaxMorph class>>testAll
runs into problems, so I am expecting that the various compiler and Spur
enhancements in recent years mean that some work would need to be done in
this area.

I am inclined to commit the current (old) version the missing methods to the
Etoys package, but I do not want to do that if they were intentionally removed
or if someone has a plan to provide a fully working update.

Dave