diff -r 000000000000 -r 6474c204b198 dom/smil/nsSMILCompositorTable.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/smil/nsSMILCompositorTable.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; 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/. */
+
+#ifndef NS_SMILCOMPOSITORTABLE_H_
+#define NS_SMILCOMPOSITORTABLE_H_
+
+#include "nsTHashtable.h"
+
+//----------------------------------------------------------------------
+// nsSMILCompositorTable : A hashmap of nsSMILCompositors
+//
+// This is just a forward-declaration because it is included in
+// nsSMILAnimationController which is used in nsDocument. We don't want to
+// expose all of nsSMILCompositor or otherwise any changes to it will mean the
+// whole world will need to be rebuilt.
+
+class nsSMILCompositor;
+typedef nsTHashtable<nsSMILCompositor> nsSMILCompositorTable;
+
+#endif // NS_SMILCOMPOSITORTABLE_H_