import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/webidl/MediaList.webidl

@@ -0,0 +1,19 @@
+/* -*- 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/. */
+
+// http://dev.w3.org/csswg/cssom/#the-medialist-interface
+
+[ArrayClass]
+interface MediaList {
+  [TreatNullAs=EmptyString]
+           attribute DOMString        mediaText;
+
+  readonly attribute unsigned long    length;
+  getter DOMString?  item(unsigned long index);
+  [Throws]
+  void               deleteMedium(DOMString oldMedium);
+  [Throws]
+  void               appendMedium(DOMString newMedium);
+};