x/net/websocket: always close underlying connection on ws.Close

Fixes #10866

When ws.Close is called, always close the underlying ws.rwc.

Change-Id: Ia709d5e0bc51ffb7194668d2764848d012e0c652
Reviewed-on: https://go-review.googlesource.com/10135
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2 files changed