entity lookup and fallback in expat

As there were more people talking about this than I recall, here's the public correction on what I though would be true:

1. I see no way to hook into expat to make it resolve an entity. See the XML_TOK_ENTITY_REF handling in xmlparse.c.
2. We can redefine entities. I'm not exactly sure on how the brand.dtd-inclusion in the neterror overrides will like this, yet.

Does hacking the chrome protocol to concat the DTD files for all available locales sound like a good idea?

And I wonder if we can revisit the XML_ERROR_UNDEFINED_ENTITY in xmlparse.c to just notify us, so that we could whine in the error console without busting.