- fix/check location of popdcl calls where questioned
- remove unnecessary handling of ... (LDDD) in ntype (couldn't be reached)
- inlined and fnret_type and simplified fnres as a consequence
- leave handling of ... (LDDD) in arg_list alone (remove TODO)
- verify that parser requires a ';' after last statement in a case/default
  (added test case)

Fixes #13243.

Change-Id: Iad94b498591a5e85f4cb15bbc01e8e101415560d
Reviewed-on: https://go-review.googlesource.com/17155
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Chris Manghane <cmang@golang.org>