use submodule

vendor/github.com/gorilla/websocket/mask_safe.go

@@ -1,15 +0,0 @@
-// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved.  Use of
-// this source code is governed by a BSD-style license that can be found in the
-// LICENSE file.
-
-// +build appengine
-
-package websocket
-
-func maskBytes(key [4]byte, pos int, b []byte) int {
-	for i := range b {
-		b[i] ^= key[pos&3]
-		pos++
-	}
-	return pos & 3
-}