Add a test that server_name extensions are parsed correctly.

Change-Id: Id4025835df49eb498df9a48fc81061541778569b
Reviewed-on: https://boringssl-review.googlesource.com/1092
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/runner.go b/ssl/test/runner/runner.go
index 2cda660..f253f89 100644
--- a/ssl/test/runner/runner.go
+++ b/ssl/test/runner/runner.go
@@ -135,6 +135,14 @@
 		},
 		flags: []string{"-fallback-scsv"},
 	},
+	{
+		testType: serverTest,
+		name: "ServerNameExtension",
+		config: Config{
+			ServerName: "example.com",
+		},
+		flags: []string{"-expect-server-name", "example.com"},
+	},
 }
 
 func doExchange(tlsConn *Conn, messageLen int) error {