import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/webidl/CSSPseudoElement.webidl

@@ -0,0 +1,25 @@
+/* -*- 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
+ * https://drafts.csswg.org/css-pseudo/#CSSPseudoElement-interface
+ * https://drafts.csswg.org/cssom/#pseudoelement
+ *
+ * Copyright © 2015 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C
+ * liability, trademark and document use rules apply.
+ */
+
+// Both CSSOM and CSS Pseudo-Elements 4 provide contradictory definitions for
+// this interface.
+// What we implement here is a minimal subset of the two definitions which we
+// ship behind a pref until the specification issues have been resolved.
+[Func="nsDocument::IsWebAnimationsEnabled"]
+interface CSSPseudoElement {
+  readonly attribute DOMString type;
+  readonly attribute Element parentElement;
+};
+
+// https://w3c.github.io/web-animations/#extensions-to-the-pseudoelement-interface
+CSSPseudoElement implements Animatable;