RFR: More cleanup patches

[Martin Buchholz]

Maybe I'm starting to understand.

            // attempt to load class in module defined to this loader
            assert loadedModule.loader() == this;
            return findClassInModuleOrNull(loadedModule, cn);

Precondition of calling findClassInModuleOrNull is that
loadedModule.loader() == this;
so perhaps move that assert into the body of findClassInModuleOrNull ?

---

        // no class loading until VM is fully initialized
        if (!VM.isModuleSystemInited())

Here the method call is so self-documenting that we should just delete the
comment?
"VM is fully initialized" is not the same as "module system is
initialized"?!