http: add Pending method to ServerConn, ClientConn
http: add Pending method to ServerConn, ClientConn

R=rsc
CC=golang-dev
http://codereview.appspot.com/216052

Committer: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

tav/go,tav/go,tav/go,tav/go,tav/go,tav/go,tav/go