net/http: remove unused test type

Change-Id: Ia8d4459a39425583027f00410fe17b9686b768db
Reviewed-on: https://go-review.googlesource.com/3026
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/http/request_test.go

@@ -402,8 +402,6 @@ type getBasicAuthTest struct {
 	ok                 bool
 }
 
-type parseBasicAuthTest getBasicAuthTest
-
 type basicAuthCredentialsTest struct {
 	username, password string
 }