--- a/content/base/public/nsISelectionPrivate.idl
+++ b/content/base/public/nsISelectionPrivate.idl
@@ -9,21 +9,23 @@
 
 interface nsRange;
 interface nsIDOMNode;
 interface nsISelectionListener;
 interface nsIContent;
 interface nsINode;
 
 %{C++
+class nsIFrame;
 struct nsTextRangeStyle;
 struct nsPoint;
 struct ScrollAxis;
+#include "nsDirection.h"
 #include "nsTArray.h"
-#include "nsIFrame.h"
+#include "nsIPresShell.h" // TODO: Remove this include
 %}
 
 [ptr] native nsIFrame(nsIFrame);
 [ptr] native RangeArray(nsTArray<nsRange*>);
 [ref] native constTextRangeStyleRef(const nsTextRangeStyle);
 [ref] native nsPointRef(nsPoint);
 native nsDirection(nsDirection);
 native ScrollAxis(nsIPresShell::ScrollAxis);

--- a/editor/libeditor/base/IMETextTxn.cpp
+++ b/editor/libeditor/base/IMETextTxn.cpp
@@ -7,16 +7,17 @@
 #include "mozilla/mozalloc.h"           // for operator new
 #include "nsAString.h"                  // for nsAString_internal::Length, etc
 #include "nsAutoPtr.h"                  // for nsRefPtr
 #include "nsDebug.h"                    // for NS_ASSERTION, etc
 #include "nsError.h"                    // for NS_SUCCEEDED, NS_FAILED, etc
 #include "nsGUIEvent.h"                 // for nsTextRangeStyle
 #include "nsIDOMCharacterData.h"        // for nsIDOMCharacterData
 #include "nsIDOMRange.h"                // for nsRange::SetEnd, etc
+#include "nsIContent.h"                 // for nsIContent
 #include "nsIEditor.h"                  // for nsIEditor
 #include "nsIPresShell.h"               // for SelectionType
 #include "nsIPrivateTextRange.h"        // for nsIPrivateTextRange, etc
 #include "nsISelection.h"               // for nsISelection
 #include "nsISelectionController.h"     // for nsISelectionController, etc
 #include "nsISelectionPrivate.h"        // for nsISelectionPrivate
 #include "nsISupportsImpl.h"            // for nsRange::AddRef, etc
 #include "nsISupportsUtils.h"           // for NS_ADDREF_THIS, NS_RELEASE

--- a/layout/generic/Selection.h
+++ b/layout/generic/Selection.h
@@ -8,21 +8,23 @@
 #define mozilla_Selection_h__
 
 #include "nsIWeakReference.h"
 
 #include "nsISelection.h"
 #include "nsISelectionController.h"
 #include "nsISelectionPrivate.h"
 #include "nsRange.h"
+#include "nsThreadUtils.h"
 
 struct CachedOffsetForFrame;
 class nsAutoScrollTimer;
 class nsIContentIterator;
 class nsIFrame;
+class nsFrameSelection;
 struct SelectionDetails;
 
 struct RangeData
 {
   RangeData(nsRange* aRange)
     : mRange(aRange)
   {}
 

--- a/layout/generic/moz.build
+++ b/layout/generic/moz.build
@@ -7,16 +7,17 @@
 TEST_DIRS += ['test']
 
 MODULE = 'layout'
 
 EXPORTS += [
     'ScrollbarActivity.h',
     'Selection.h',
     'nsCanvasFrame.h',
+    'nsDirection.h',
     'nsFrameIdList.h',
     'nsFrameList.h',
     'nsFrameSelection.h',
     'nsHTMLParts.h',
     'nsHTMLReflowMetrics.h',
     'nsHTMLReflowState.h',
     'nsIAnonymousContentCreator.h',
     'nsIFrame.h',

new file mode 100644
--- /dev/null
+++ b/layout/generic/nsDirection.h
@@ -0,0 +1,19 @@
+/* -*- 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 nsDirection_h___
+#define nsDirection_h___
+
+// This file makes the nsDirection enum present both in nsIFrame.h and
+// nsISelectionPrivate.h.
+
+enum nsDirection {
+  eDirNext    = 0,
+  eDirPrevious= 1
+};
+
+#endif
+

--- a/layout/generic/nsIFrame.h
+++ b/layout/generic/nsIFrame.h
@@ -28,16 +28,17 @@
 #include "nsHTMLReflowMetrics.h"
 #include "nsFrameList.h"
 #include "nsIContent.h"
 #include "nsAlgorithm.h"
 #include "mozilla/layout/FrameChildList.h"
 #include "mozilla/css/ImageLoader.h"
 #include "FramePropertyTable.h"
 #include "mozilla/TypedEnum.h"
+#include "nsDirection.h"
 #include <algorithm>
 
 #ifdef ACCESSIBILITY
 #include "mozilla/a11y/AccTypes.h"
 #endif
 
 /**
  * New rules of reflow:
@@ -350,21 +351,16 @@ enum nsSelectionAmount {
   eSelectEndLine   = 5,
   eSelectNoAmount  = 6, // just bounce back current offset.
   eSelectParagraph = 7,  // select a "paragraph"
   eSelectWordNoSpace = 8 // select a "word" without selecting the following
                          // space, no matter what the default platform
                          // behavior is
 };
 
-enum nsDirection {
-  eDirNext    = 0,
-  eDirPrevious= 1
-};
-
 enum nsSpread {
   eSpreadNone   = 0,
   eSpreadAcross = 1,
   eSpreadDown   = 2
 };
 
 // Carried out margin flags
 #define NS_CARRIED_TOP_MARGIN_IS_AUTO    0x1