bug#3310: condition-case-no-debug

[Johan =?UTF-8?Q?Bockg=C3=A5rd]

condition-case-no-debug is not documented, either in the manual or in
NEWS. Also, there's another feature that does the same thing, except
better (if uglier):

    (condition-case nil (foo bar) ((debug error) nil))

This handles errors but gives the debugger a chance to run first.
condition-case-no-debug OTOH either handles errors, or lets the debugger
run but does not handle errors, depending on the value of debug-on-error.

If condition-case-no-debug should be kept, at least make it expand into
the above construct (and document it).