import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/webidl/TextEncoder.webidl

@@ -0,0 +1,20 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * The origin of this IDL file is
+ * http://encoding.spec.whatwg.org/#interface-textencoder
+ *
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+[Constructor,
+ Exposed=(Window,Worker,System)]
+interface TextEncoder {
+  [Constant]
+  readonly attribute DOMString encoding;
+  [NewObject]
+  Uint8Array encode(optional USVString input = "");
+};