* nxml/rng-valid.el (rng-validate-mode): Don't hardcode point-min==1.
(rng-compute-mode-line-string): Show the validation percentage in
terms of the narrowed text, not the widened text.
(rng-do-some-validation): Don't catch internal errors when debugging.
(rng-first-error): Simplify.
(rng-after-change-function): Remove work around. AFAIK the bug has
been fixed a while ago.