The exp/proxy package was removed from the master library in
    https://golang.org/cl/6461056 (August, 2012).
    
    The exp/terminal package was removed from the master library in
    https://golang.org/cl/5970044 (March, 2012).
    
    I'm not sure why they lingered in the gofrontend copy, but let's
    finally remove them now.
    
    Reviewed-on: https://go-review.googlesource.com/87138

From-SVN: r256435