Simplify slice/map literal expressions.
Caught with gofmt -d -s, fixed with gofmt -w -s
Checked that the result can still be compiled with Go 1.4.

Change-Id: I06bce110bb5f46ee2f45113681294475aa6968bc
Reviewed-on: https://go-review.googlesource.com/13839Reviewed-by: Andrew Gerrand <adg@golang.org>