--- a/layout/base/moz.build
+++ b/layout/base/moz.build
@@ -54,17 +54,16 @@ EXPORTS += [
     'nsIPercentBSizeObserver.h',
     'nsIPresShell.h',
     'nsIPresShellInlines.h',
     'nsIReflowCallback.h',
     'nsLayoutUtils.h',
     'nsPresArena.h',
     'nsPresArenaObjectList.h',
     'nsPresContext.h',
-    'nsPresState.h',
     'nsQuoteList.h',
     'nsRefreshDriver.h',
     'nsStyleChangeList.h',
     'nsStyleSheetService.h',
     'ScrollbarStyles.h',
     'StackArena.h',
     'TouchManager.h',
     'Units.h',

deleted file mode 100644
--- a/layout/base/nsPresState.h
+++ /dev/null
@@ -1,127 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* vim: set ts=8 sts=2 et sw=2 tw=80: */
-/* 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/. */
-
-/*
- * a piece of state that is stored in session history when the document
- * is not
- */
-
-#ifndef nsPresState_h_
-#define nsPresState_h_
-
-#include "nsPoint.h"
-#include "gfxPoint.h"
-#include "nsAutoPtr.h"
-
-class nsPresState
-{
-public:
-  nsPresState()
-    : mContentData(nullptr)
-    , mScrollState(0, 0)
-    , mAllowScrollOriginDowngrade(true)
-    , mResolution(1.0)
-    , mScaleToResolution(false)
-    , mDisabledSet(false)
-    , mDisabled(false)
-    , mDroppedDown(false)
-  {}
-
-  void SetScrollState(const nsPoint& aState)
-  {
-    mScrollState = aState;
-  }
-
-  nsPoint GetScrollPosition() const
-  {
-    return mScrollState;
-  }
-
-  void SetAllowScrollOriginDowngrade(bool aAllowScrollOriginDowngrade)
-  {
-    mAllowScrollOriginDowngrade = aAllowScrollOriginDowngrade;
-  }
-
-  bool GetAllowScrollOriginDowngrade()
-  {
-    return mAllowScrollOriginDowngrade;
-  }
-
-  void SetResolution(float aSize)
-  {
-    mResolution = aSize;
-  }
-
-  float GetResolution() const
-  {
-    return mResolution;
-  }
-
-  void SetScaleToResolution(bool aScaleToResolution)
-  {
-    mScaleToResolution = aScaleToResolution;
-  }
-
-  bool GetScaleToResolution() const
-  {
-    return mScaleToResolution;
-  }
-
-  void ClearNonScrollState()
-  {
-    mContentData = nullptr;
-    mDisabledSet = false;
-  }
-
-  bool GetDisabled() const
-  {
-    return mDisabled;
-  }
-
-  void SetDisabled(bool aDisabled)
-  {
-    mDisabled = aDisabled;
-    mDisabledSet = true;
-  }
-
-  bool IsDisabledSet() const
-  {
-    return mDisabledSet;
-  }
-
-  nsISupports* GetStateProperty() const
-  {
-    return mContentData;
-  }
-
-  void SetStateProperty(nsISupports *aProperty)
-  {
-    mContentData = aProperty;
-  }
-
-  void SetDroppedDown(bool aDroppedDown)
-  {
-    mDroppedDown = aDroppedDown;
-  }
-
-  bool GetDroppedDown() const
-  {
-    return mDroppedDown;
-  }
-
-// MEMBER VARIABLES
-protected:
-  nsCOMPtr<nsISupports> mContentData;
-  nsPoint mScrollState;
-  bool mAllowScrollOriginDowngrade;
-  float mResolution;
-  bool mScaleToResolution;
-  bool mDisabledSet;
-  bool mDisabled;
-  bool mDroppedDown;
-};
-
-#endif /* nsPresState_h_ */

--- a/xpcom/base/ErrorList.py
+++ b/xpcom/base/ErrorList.py
@@ -469,21 +469,16 @@ with modules["PLUGINS"]:
 # =======================================================================
 with modules["LAYOUT"]:
     # Return code for nsITableLayout
     errors["NS_TABLELAYOUT_CELL_NOT_FOUND"] = SUCCESS(0)
     # Return code for SheetLoadData::VerifySheetReadyToParse
     errors["NS_OK_PARSE_SHEET"] = SUCCESS(1)
     # Return code for nsFrame::GetNextPrevLineFromeBlockFrame
     errors["NS_POSITION_BEFORE_TABLE"] = SUCCESS(3)
-    # Return codes for nsPresState::GetProperty()
-    # Returned if the property exists
-    errors["NS_STATE_PROPERTY_EXISTS"] = errors["NS_OK"]
-    # Returned if the property does not exist
-    errors["NS_STATE_PROPERTY_NOT_THERE"] = SUCCESS(5)
 
 
 
 # =======================================================================
 # 9: NS_ERROR_MODULE_HTMLPARSER
 # =======================================================================
 with modules["HTMLPARSER"]:
     errors["NS_ERROR_HTMLPARSER_CONTINUE"] = errors["NS_OK"]