Follow up to CL 29134. Generated with gofmt -r 'Nod -> nod', plus
three manual adjustments to the comments in syntax/parser.go

Change-Id: I02920f7ab10c70b6e850457b42d5fe35f1f3821a
Reviewed-on: https://go-review.googlesource.com/29136Reviewed-by: Matthew Dempsky <mdempsky@google.com>