[dvipdfmx] missing annotation rectangle if the box contains no glyph

[Shunsaku Hirata]

> Yes, but what I meant is, what would happen if such a special is
> outside a bann/eann? Is it then simply ignored (and so harmless) or
> will it confuse xdvipdfmx (and so should be avoided)?

And for this, it can be simply ignored.

Thanks,
Shunsaku Hirata