[XeTeX] xdvipdfmx fails on synthetically-slanted fonts

[Akira Kakuto]

> C>xdvipdfmx pev.xdv
> pev.xdv -> pev.pdf
> [1
> ** ERROR ** TFM: Invalid TFM ID: 0
> 
> Output file removed.
> 
> Source file:
> % plain XeTeX
> \font\inconsN="Inconsolata"
> \font\inconsS="Inconsolata:slant=0.2"
> \inconsN This is {\inconsS merely} a test.
> \bye

If cmr10 is used first,
xdvipdfmx -o pev1.pdf pev.xdv
ends without error message, but pev1.pdf is strange.
pev2.pdf obtained by
xdvipdfmx -o pev2.pdf <pev.xdv
seems to be ok.

% plain XeTeX
This is a test.

\font\inconsN="Inconsolata"
\font\inconsS="Inconsolata:slant=0.2"
\inconsN This is {\inconsS merely} a test.
\bye

Best,
Akira