And some double space after period cleanup while I'm here.
I guess my previous regexps missed these. My next cleaner should
probably use go/ast instead of perl.

Updates #20221

Change-Id: Idb051e7ac3a7fb1fb86e015f709e32139d065d92
Reviewed-on: https://go-review.googlesource.com/47094Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Rob Pike <r@golang.org>