diff -r 000000000000 -r 6474c204b198 layout/generic/nsIFrameInlines.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/generic/nsIFrameInlines.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et tw=78: */
+/* 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 nsIFrameInlines_h___
+#define nsIFrameInlines_h___
+
+#include "nsIFrame.h"
+#include "nsStyleStructInlines.h"
+
+bool
+nsIFrame::IsFlexItem() const
+{
+  return mParent &&
+    mParent->GetType() == nsGkAtoms::flexContainerFrame &&
+    !(GetStateBits() & NS_FRAME_OUT_OF_FLOW);
+}
+
+bool
+nsIFrame::IsFloating() const
+{
+  return StyleDisplay()->IsFloating(this);
+}
+
+bool
+nsIFrame::IsPositioned() const
+{
+  return StyleDisplay()->IsPositioned(this);
+}
+
+bool
+nsIFrame::IsRelativelyPositioned() const
+{
+  return StyleDisplay()->IsRelativelyPositioned(this);
+}
+
+bool
+nsIFrame::IsAbsolutelyPositioned() const
+{
+  return StyleDisplay()->IsAbsolutelyPositioned(this);
+}
+
+bool
+nsIFrame::IsBlockInside() const
+{
+  return StyleDisplay()->IsBlockInside(this);
+}
+
+bool
+nsIFrame::IsBlockOutside() const
+{
+  return StyleDisplay()->IsBlockOutside(this);
+}
+
+bool
+nsIFrame::IsInlineOutside() const
+{
+  return StyleDisplay()->IsInlineOutside(this);
+}
+
+uint8_t
+nsIFrame::GetDisplay() const
+{
+  return StyleDisplay()->GetDisplay(this);
+}
+
+#endif