--- a/accessible/html/HTMLTableAccessible.cpp
+++ b/accessible/html/HTMLTableAccessible.cpp
@@ -14,17 +14,16 @@
 #include "nsTextEquivUtils.h"
 #include "Relation.h"
 #include "Role.h"
 #include "States.h"
 #include "TreeWalker.h"
 
 #include "mozilla/dom/HTMLTableElement.h"
 #include "nsIDOMRange.h"
-#include "nsISelectionPrivate.h"
 #include "nsIHTMLCollection.h"
 #include "nsIDocument.h"
 #include "nsIMutableArray.h"
 #include "nsIPersistentProperties2.h"
 #include "nsIPresShell.h"
 #include "nsITableCellLayout.h"
 #include "nsFrameSelection.h"
 #include "nsError.h"

--- a/accessible/html/HTMLTableAccessible.h
+++ b/accessible/html/HTMLTableAccessible.h
@@ -177,17 +177,17 @@ protected:
 
   // HTMLTableAccessible
 
   /**
    * Add row or column to selection.
    *
    * @param aIndex   [in] index of row or column to be selected
    * @param aTarget  [in] indicates what should be selected, either row or column
-   *                  (see nsISelectionPrivate)
+   *                  (see nsFrameSelection)
    */
   nsresult AddRowOrColumnToSelection(int32_t aIndex, TableSelection aTarget);
 
   /**
    * Removes rows or columns at the given index or outside it from selection.
    *
    * @param  aIndex    [in] row or column index
    * @param  aTarget   [in] indicates whether row or column should unselected

--- a/dom/base/Selection.cpp
+++ b/dom/base/Selection.cpp
@@ -758,17 +758,16 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSelectionListeners)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(Selection)
 
 // QueryInterface implementation for Selection
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Selection)
   NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
   NS_INTERFACE_MAP_ENTRY(nsISelection)
-  NS_INTERFACE_MAP_ENTRY(nsISelectionPrivate)
   NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
   NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsISelection)
 NS_INTERFACE_MAP_END
 
 NS_IMPL_MAIN_THREAD_ONLY_CYCLE_COLLECTING_ADDREF(Selection)
 NS_IMPL_MAIN_THREAD_ONLY_CYCLE_COLLECTING_RELEASE(Selection)
 
 const RangeBoundary&

--- a/dom/base/Selection.h
+++ b/dom/base/Selection.h
@@ -9,21 +9,23 @@
 
 #include "nsIWeakReference.h"
 
 #include "mozilla/AutoRestore.h"
 #include "mozilla/RangeBoundary.h"
 #include "mozilla/TextRange.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WeakPtr.h"
+#include "nsDirection.h"
+#include "nsIPresShell.h"  // For ScrollAxis
 #include "nsISelection.h"
 #include "nsISelectionController.h"
 #include "nsISelectionListener.h"
-#include "nsISelectionPrivate.h"
 #include "nsRange.h"
+#include "nsTArrayForwardDeclare.h"
 #include "nsThreadUtils.h"
 #include "nsWrapperCache.h"
 
 struct CachedOffsetForFrame;
 class nsAutoScrollTimer;
 class nsIContentIterator;
 class nsIDocument;
 class nsIFrame;
@@ -59,33 +61,31 @@ namespace dom {
 
 // Note, the ownership of mozilla::dom::Selection depends on which way the
 // object is created. When nsFrameSelection has created Selection,
 // addreffing/releasing the Selection object is aggregated to nsFrameSelection.
 // Otherwise normal addref/release is used.  This ensures that nsFrameSelection
 // is never deleted before its Selections.
 class Selection final : public nsISelection,
                         public nsWrapperCache,
-                        public nsISelectionPrivate,
                         public nsSupportsWeakReference,
                         public SupportsWeakPtr<Selection>
 {
 protected:
   virtual ~Selection();
 
 public:
   Selection();
   explicit Selection(nsFrameSelection *aList);
 
   MOZ_DECLARE_WEAKREFERENCE_TYPENAME(Selection)
 
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(Selection, nsISelection)
   NS_DECL_NSISELECTION
-  NS_DECL_NSISELECTIONPRIVATE
 
   // match this up with EndbatchChanges. will stop ui updates while multiple
   // selection methods are called
   void StartBatchChanges();
 
   // match this up with StartBatchChanges
   void EndBatchChanges(int16_t aReason = nsISelectionListener::NO_REASON);
 

--- a/dom/base/SelectionChangeListener.h
+++ b/dom/base/SelectionChangeListener.h
@@ -3,17 +3,16 @@
 /* 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 mozilla_SelectionChangeListener_h_
 #define mozilla_SelectionChangeListener_h_
 
 #include "nsISelectionListener.h"
-#include "nsISelectionPrivate.h"
 #include "mozilla/Attributes.h"
 
 namespace mozilla {
 namespace dom {
 
 class SelectionChangeListener final : public nsISelectionListener
 {
 public:

--- a/dom/base/moz.build
+++ b/dom/base/moz.build
@@ -24,17 +24,16 @@ XPIDL_SOURCES += [
     'nsIObjectLoadingContent.idl',
     'nsIPerformanceMetrics.idl',
     'nsIRemoteWindowContext.idl',
     'nsIScriptChannel.idl',
     'nsISelection.idl',
     'nsISelectionController.idl',
     'nsISelectionDisplay.idl',
     'nsISelectionListener.idl',
-    'nsISelectionPrivate.idl',
     'nsISlowScriptDebug.idl',
 ]
 
 XPIDL_MODULE = 'dom'
 
 EXPORTS += [
     'AutocompleteFieldList.h',
     'Crypto.h',

--- a/dom/base/nsDocumentEncoder.cpp
+++ b/dom/base/nsDocumentEncoder.cpp
@@ -23,17 +23,16 @@
 #include "nsRange.h"
 #include "nsIDOMDocument.h"
 #include "nsGkAtoms.h"
 #include "nsIContent.h"
 #include "nsIScriptContext.h"
 #include "nsIScriptGlobalObject.h"
 #include "nsIScriptSecurityManager.h"
 #include "mozilla/dom/Selection.h"
-#include "nsISelectionPrivate.h"
 #include "nsITransferable.h" // for kUnicodeMime
 #include "nsContentUtils.h"
 #include "nsElementTable.h"
 #include "nsNodeUtils.h"
 #include "nsUnicharUtils.h"
 #include "nsReadableUtils.h"
 #include "nsTArray.h"
 #include "nsIFrame.h"

deleted file mode 100644
--- a/dom/base/nsISelectionPrivate.idl
+++ /dev/null
@@ -1,35 +0,0 @@
-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
-/* 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/. */
-
-#include "nsISelection.idl"
-
-interface nsRange;
-interface nsIDOMNode;
-interface nsISelectionListener;
-interface nsIContent;
-interface nsINode;
-interface nsIDOMRange;
-
-%{C++
-class nsIFrame;
-struct nsPoint;
-struct ScrollAxis;
-#include "nsDirection.h"
-#include "nsIPresShell.h" // TODO: Remove this include
-#include "nsTArrayForwardDeclare.h"
-#include "mozilla/EventForwards.h"
-%}
-
-[ptr] native nsIFrame(nsIFrame);
-[ptr] native RangeArray(nsTArray<nsRange*>);
-[ref] native nsPointRef(nsPoint);
-native nsDirection(nsDirection);
-native ScrollAxis(nsIPresShell::ScrollAxis);
-
-[uuid(0c9f4f74-ee7e-4fe9-be6b-0ba856368178)]
-interface nsISelectionPrivate : nsISupports
-{
-};
-

--- a/dom/html/nsHTMLDocument.cpp
+++ b/dom/html/nsHTMLDocument.cpp
@@ -55,17 +55,16 @@
 #include "nsIComponentManager.h"
 #include "nsParserCIID.h"
 #include "nsNameSpaceManager.h"
 #include "nsGenericHTMLElement.h"
 #include "mozilla/css/Loader.h"
 #include "nsIHttpChannel.h"
 #include "nsIFile.h"
 #include "nsFrameSelection.h"
-#include "nsISelectionPrivate.h" //for toStringwithformat code
 
 #include "nsContentUtils.h"
 #include "nsJSUtils.h"
 #include "nsIDocumentInlines.h"
 #include "nsIDocumentEncoder.h" //for outputting selection
 #include "nsICachingChannel.h"
 #include "nsIContentViewer.h"
 #include "nsIWyciwygChannel.h"

--- a/dom/html/nsTextEditorState.cpp
+++ b/dom/html/nsTextEditorState.cpp
@@ -22,17 +22,16 @@
 #include "nsIControllerContext.h"
 #include "nsAttrValue.h"
 #include "nsAttrValueInlines.h"
 #include "nsGenericHTMLElement.h"
 #include "nsIDOMEventListener.h"
 #include "nsIEditorObserver.h"
 #include "nsIWidget.h"
 #include "nsIDocumentEncoder.h"
-#include "nsISelectionPrivate.h"
 #include "nsPIDOMWindow.h"
 #include "nsServiceManagerUtils.h"
 #include "mozilla/dom/Selection.h"
 #include "mozilla/TextEditRules.h"
 #include "mozilla/EventListenerManager.h"
 #include "nsContentUtils.h"
 #include "mozilla/Preferences.h"
 #include "nsTextNode.h"

--- a/dom/webidl/Selection.webidl
+++ b/dom/webidl/Selection.webidl
@@ -71,17 +71,17 @@ interface Selection {
 
 // Additional methods not currently in the spec
 partial interface Selection {
   [Throws]
   void modify(DOMString alter, DOMString direction,
               DOMString granularity);
 };
 
-// Additional chrome-only methods from nsISelectionPrivate
+// Additional chrome-only methods.
 interface nsISelectionListener;
 partial interface Selection {
   /**
    * A true value means "selection after newline"; false means "selection before
    * newline" when a selection is positioned "between lines".
    */
   [ChromeOnly,Throws]
   attribute boolean interlinePosition;

--- a/editor/composer/nsEditingSession.cpp
+++ b/editor/composer/nsEditingSession.cpp
@@ -32,17 +32,16 @@
 #include "nsIEditor.h"                  // for nsIEditor
 #include "nsIHTMLDocument.h"            // for nsIHTMLDocument, etc
 #include "nsIInterfaceRequestorUtils.h"  // for do_GetInterface
 #include "nsIPlaintextEditor.h"         // for nsIPlaintextEditor, etc
 #include "nsIPresShell.h"               // for nsIPresShell
 #include "nsIRefreshURI.h"              // for nsIRefreshURI
 #include "nsIRequest.h"                 // for nsIRequest
 #include "nsISelection.h"               // for nsISelection
-#include "nsISelectionPrivate.h"        // for nsISelectionPrivate
 #include "nsITimer.h"                   // for nsITimer, etc
 #include "nsITransactionManager.h"      // for nsITransactionManager
 #include "nsIWeakReference.h"           // for nsISupportsWeakReference, etc
 #include "nsIWebNavigation.h"           // for nsIWebNavigation
 #include "nsIWebProgress.h"             // for nsIWebProgress, etc
 #include "nsLiteralString.h"            // for NS_LITERAL_STRING
 #include "nsPICommandUpdater.h"         // for nsPICommandUpdater
 #include "nsPIDOMWindow.h"              // for nsPIDOMWindow

--- a/layout/base/nsCaret.cpp
+++ b/layout/base/nsCaret.cpp
@@ -14,17 +14,16 @@
 #include "mozilla/gfx/2D.h"
 #include "nsCOMPtr.h"
 #include "nsFontMetrics.h"
 #include "nsITimer.h"
 #include "nsFrameSelection.h"
 #include "nsIFrame.h"
 #include "nsIScrollableFrame.h"
 #include "nsIDOMNode.h"
-#include "nsISelectionPrivate.h"
 #include "nsIContent.h"
 #include "nsIPresShell.h"
 #include "nsLayoutUtils.h"
 #include "nsPresContext.h"
 #include "nsBlockFrame.h"
 #include "nsISelectionController.h"
 #include "nsTextFrame.h"
 #include "nsXULPopupManager.h"

--- a/layout/generic/nsDirection.h
+++ b/layout/generic/nsDirection.h
@@ -3,17 +3,17 @@
 /* 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.
+// Selection.h.
 
 enum nsDirection {
   eDirNext    = 0,
   eDirPrevious= 1
 };
 
 #endif
 

--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -45,17 +45,16 @@
 #include "nsIPresShell.h"
 #include "mozilla/Logging.h"
 #include "mozilla/Sprintf.h"
 #include "nsLayoutUtils.h"
 #include "LayoutLogging.h"
 #include "mozilla/RestyleManager.h"
 #include "nsInlineFrame.h"
 #include "nsIDOMNode.h"
-#include "nsISelectionPrivate.h"
 #include "nsFrameSelection.h"
 #include "nsGkAtoms.h"
 #include "nsCSSAnonBoxes.h"
 #include "nsCSSClipPathInstance.h"
 
 #include "nsFrameTraversal.h"
 #include "nsRange.h"
 #include "nsITextControlFrame.h"

--- a/layout/printing/nsPrintJob.cpp
+++ b/layout/printing/nsPrintJob.cpp
@@ -74,17 +74,16 @@ static const char kPrintingPromptService
 #include "gfxContext.h"
 #include "mozilla/gfx/DrawEventRecorder.h"
 #include "mozilla/layout/RemotePrintJobChild.h"
 #include "nsISupportsUtils.h"
 #include "nsIScriptContext.h"
 #include "nsIDOMDocument.h"
 #include "nsIDocumentObserver.h"
 #include "nsISelectionListener.h"
-#include "nsISelectionPrivate.h"
 #include "nsContentCID.h"
 #include "nsLayoutCID.h"
 #include "nsContentUtils.h"
 #include "nsIPresShell.h"
 #include "nsLayoutStylesheetCache.h"
 #include "nsLayoutUtils.h"
 #include "mozilla/Preferences.h"
 #include "Text.h"

--- a/widget/nsBaseDragService.cpp
+++ b/widget/nsBaseDragService.cpp
@@ -14,17 +14,16 @@
 #include "nsCOMPtr.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsIFrame.h"
 #include "nsIDocument.h"
 #include "nsIContent.h"
 #include "nsIPresShell.h"
 #include "nsViewManager.h"
 #include "nsIDOMNode.h"
-#include "nsISelectionPrivate.h"
 #include "nsPresContext.h"
 #include "nsIImageLoadingContent.h"
 #include "imgIContainer.h"
 #include "imgIRequest.h"
 #include "ImageRegion.h"
 #include "nsQueryObject.h"
 #include "nsRegion.h"
 #include "nsXULPopupManager.h"