diff -r 000000000000 -r 6474c204b198 layout/style/nsStyleStructFwd.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/style/nsStyleStructFwd.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,67 @@
+/* -*- 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/. */
+
+/*
+ * Forward declarations to avoid including all of nsStyleStruct.h.
+ */
+
+#ifndef nsStyleStructFwd_h_
+#define nsStyleStructFwd_h_
+
+enum nsStyleStructID {
+
+/*
+ * Define the constants eStyleStruct_Font, etc.
+ *
+ * The C++ standard, section 7.2, guarantees that enums begin with 0 and
+ * increase by 1.
+ *
+ * We separate the IDs of Reset and Inherited structs so that we can use
+ * the IDs as indices (offset by nsStyleStructID_*_Start) into arrays of
+ * one type or the other.
+ */
+
+nsStyleStructID_Inherited_Start = 0,
+// a dummy value so the value after it is the same as ..._Inherited_Start
+nsStyleStructID_DUMMY1 = nsStyleStructID_Inherited_Start - 1,
+
+#define STYLE_STRUCT_INHERITED(name, checkdata_cb) \
+  eStyleStruct_##name,
+#define STYLE_STRUCT_RESET(name, checkdata_cb)
+#include "nsStyleStructList.h"
+#undef STYLE_STRUCT_INHERITED
+#undef STYLE_STRUCT_RESET
+
+nsStyleStructID_Reset_Start,
+// a dummy value so the value after it is the same as ..._Reset_Start
+nsStyleStructID_DUMMY2 = nsStyleStructID_Reset_Start - 1,
+
+#define STYLE_STRUCT_RESET(name, checkdata_cb) \
+  eStyleStruct_##name,
+#define STYLE_STRUCT_INHERITED(name, checkdata_cb)
+#include "nsStyleStructList.h"
+#undef STYLE_STRUCT_INHERITED
+#undef STYLE_STRUCT_RESET
+
+// one past the end; length of 0-based list
+nsStyleStructID_Length,
+
+nsStyleStructID_Inherited_Count =
+  nsStyleStructID_Reset_Start - nsStyleStructID_Inherited_Start,
+nsStyleStructID_Reset_Count =
+  nsStyleStructID_Length - nsStyleStructID_Reset_Start,
+
+// An ID used for properties that are not in style structs.  This is
+// used only in some users of nsStyleStructID, such as
+// nsCSSProps::kSIDTable, including some that store SIDs in a bitfield,
+// such as nsCSSCompressedDataBlock::mStyleBits.
+eStyleStruct_BackendOnly = nsStyleStructID_Length
+
+};
+
+// A bit corresponding to each struct ID
+#define NS_STYLE_INHERIT_BIT(sid_)        (1 << uint64_t(eStyleStruct_##sid_))
+
+#endif /* nsStyleStructFwd_h_ */