diff -r 000000000000 -r 6474c204b198 layout/generic/nsFrameState.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/generic/nsFrameState.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,105 @@
+/* -*- 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/. */
+
+/* constants for frame state bits and a type to store them in a uint64_t */
+
+#ifndef nsFrameState_h_
+#define nsFrameState_h_
+
+#include <stdint.h>
+
+#ifdef DEBUG
+#include "nsString.h"
+
+class nsIFrame;
+#endif
+
+typedef uint64_t nsFrameState_size_t;
+
+#define NS_FRAME_STATE_BIT(n_) (nsFrameState(nsFrameState_size_t(1) << (n_)))
+
+#if (_MSC_VER == 1600)
+/*
+ * Visual Studio 2010 has trouble with the sized enum.  Although sized enums
+ * are supported, two problems arise:
+ *
+ *   1. Implicit conversions from the enum type to the equivalently sized
+ *      integer size are not performed, leading to many compile errors.
+ *   2. Even with explicit casts added to avoid the errors from (1), odd
+ *      test failures result, which might well be due to a compiler bug.
+ *
+ * So with VS2010 we use consts for the state bits and forgo the increased
+ * type safety of the enum.  (Visual Studio 2012 has no problem with
+ * nsFrameState being a sized enum, however.)
+ */
+
+typedef nsFrameState_size_t nsFrameState;
+
+#define FRAME_STATE_BIT(group_, value_, name_) \
+const nsFrameState name_ = NS_FRAME_STATE_BIT(value_);
+#include "nsFrameStateBits.h"
+#undef FRAME_STATE_BIT
+
+#else
+
+enum nsFrameState : nsFrameState_size_t {
+#define FRAME_STATE_BIT(group_, value_, name_) \
+  name_ = NS_FRAME_STATE_BIT(value_),
+#include "nsFrameStateBits.h"
+#undef FRAME_STATE_BIT
+};
+
+inline nsFrameState operator|(nsFrameState aLeft, nsFrameState aRight)
+{
+  return nsFrameState(nsFrameState_size_t(aLeft) | nsFrameState_size_t(aRight));
+}
+
+inline nsFrameState operator&(nsFrameState aLeft, nsFrameState aRight)
+{
+  return nsFrameState(nsFrameState_size_t(aLeft) & nsFrameState_size_t(aRight));
+}
+
+inline nsFrameState& operator|=(nsFrameState& aLeft, nsFrameState aRight)
+{
+  aLeft = aLeft | aRight;
+  return aLeft;
+}
+
+inline nsFrameState& operator&=(nsFrameState& aLeft, nsFrameState aRight)
+{
+  aLeft = aLeft & aRight;
+  return aLeft;
+}
+
+inline nsFrameState operator~(nsFrameState aRight)
+{
+  return nsFrameState(~nsFrameState_size_t(aRight));
+}
+
+inline nsFrameState operator^(nsFrameState aLeft, nsFrameState aRight)
+{
+  return nsFrameState(nsFrameState_size_t(aLeft) ^ nsFrameState_size_t(aRight));
+}
+
+inline nsFrameState& operator^=(nsFrameState& aLeft, nsFrameState aRight)
+{
+  aLeft = aLeft ^ aRight;
+  return aLeft;
+}
+
+#endif
+
+// Bits 20-31 and 60-63 of the frame state are reserved for implementations.
+#define NS_FRAME_IMPL_RESERVED                      nsFrameState(0xF0000000FFF00000)
+#define NS_FRAME_RESERVED                           ~NS_FRAME_IMPL_RESERVED
+
+namespace mozilla {
+#ifdef DEBUG
+nsCString GetFrameState(nsIFrame* aFrame);
+void PrintFrameState(nsIFrame* aFrame);
+#endif
+}
+
+#endif /* nsFrameState_h_ */