net/http: fix comment change omitted between versions of CL 143177

Updates #23689

Change-Id: Icddec2fcc39802cacd651a9c94290e86cf1e48d1
Reviewed-on: https://go-review.googlesource.com/c/144517Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/net/http/server.go

@@ -1782,11 +1782,9 @@ func (c *conn) serve(ctx context.Context) {
 			c.rwc.SetWriteDeadline(time.Now().Add(d))
 		}
 		if err := tlsConn.Handshake(); err != nil {
-			// If the handshake failed, one reason might be a
-			// misconfigured client sending an HTTP request. If so, reach
-			// into the *tls.Conn unexported fields in a gross way so we
-			// can reply on the plaintext connection. At least there's a
-			// test that'll break if we rearrange the *tls.Conn struct.
+			// If the handshake failed due to the client not speaking
+			// TLS, assume they're speaking plaintext HTTP and write a
+			// 400 response on the TLS conn's underlying net.Conn.
 			if re, ok := err.(tls.RecordHeaderError); ok && re.Conn != nil && tlsRecordHeaderLooksLikeHTTP(re.RecordHeader) {
 				io.WriteString(re.Conn, "HTTP/1.0 400 Bad Request\r\n\r\nClient sent an HTTP request to an HTTPS server.\n")
 				re.Conn.Close()