go.tools/playground/socket: add Native Client wrapper handling
go.tools/playground/socket: add Native Client wrapper handling

LGTM=adg
R=adg, dave, rsc, minux
CC=golang-codereviews
https://codereview.appspot.com/77240043

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

karmakaze/go.tools,karmakaze/go.tools,karmakaze/go.tools,karmakaze/go.tools,karmakaze/go.tools