--- a/layout/xul/moz.build
+++ b/layout/xul/moz.build
@@ -12,17 +12,16 @@ with Files('*Menu*'):
 
 if CONFIG['ENABLE_TESTS']:
     MOCHITEST_MANIFESTS += ['test/mochitest.ini']
     MOCHITEST_CHROME_MANIFESTS += ['test/chrome.ini']
     BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 
 XPIDL_SOURCES += [
     'nsIBoxObject.idl',
-    'nsIContainerBoxObject.idl',
     'nsIListBoxObject.idl',
     'nsIMenuBoxObject.idl',
     'nsIScrollBoxObject.idl',
     'nsISliderListener.idl',
 ]
 
 XPIDL_MODULE = 'layout_xul'
 

deleted file mode 100644
--- a/layout/xul/nsIContainerBoxObject.idl
+++ /dev/null
@@ -1,14 +0,0 @@
-/* -*- 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/. */
-
-#include "nsISupports.idl"
-
-// DEPRECATED: This file exists for shim purposes only,
-// see ContainerBoxObject.webidl
-
-[uuid(35d4c04b-3bd3-4375-92e2-a818b4b4acb6)]
-interface nsIContainerBoxObject : nsISupports
-{
-};

--- a/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp
+++ b/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp
@@ -2,17 +2,16 @@
  * vim: set ts=8 sw=4 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/. */
 
 #include "ShimInterfaceInfo.h"
 
-#include "nsIContainerBoxObject.h"
 #include "nsIDOMCanvasRenderingContext2D.h"
 #include "nsIDOMCharacterData.h"
 #include "nsIDOMClientRect.h"
 #include "nsIDOMClientRectList.h"
 #include "nsIDOMClipboardEvent.h"
 #include "nsIDOMComment.h"
 #include "nsIDOMCustomEvent.h"
 #ifdef MOZ_WEBRTC
@@ -67,17 +66,16 @@
 #include "nsIXMLHttpRequest.h"
 
 #include "mozilla/dom/CanvasRenderingContext2DBinding.h"
 #include "mozilla/dom/CharacterDataBinding.h"
 #include "mozilla/dom/DOMRectBinding.h"
 #include "mozilla/dom/DOMRectListBinding.h"
 #include "mozilla/dom/ClipboardEventBinding.h"
 #include "mozilla/dom/CommentBinding.h"
-#include "mozilla/dom/ContainerBoxObjectBinding.h"
 #include "mozilla/dom/CSSPrimitiveValueBinding.h"
 #include "mozilla/dom/CSSStyleDeclarationBinding.h"
 #include "mozilla/dom/CSSStyleSheetBinding.h"
 #include "mozilla/dom/CSSValueBinding.h"
 #include "mozilla/dom/CSSValueListBinding.h"
 #include "mozilla/dom/CustomEventBinding.h"
 #ifdef MOZ_WEBRTC
 #include "mozilla/dom/DataChannelBinding.h"
@@ -200,17 +198,16 @@ struct ComponentsInterfaceShimEntry {
 const ComponentsInterfaceShimEntry kComponentsInterfaceShimMap[] =
 {
   DEFINE_SHIM(CanvasRenderingContext2D),
   DEFINE_SHIM(CharacterData),
   DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMClientRect, DOMRectReadOnly),
   DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMClientRectList, DOMRectList),
   DEFINE_SHIM(ClipboardEvent),
   DEFINE_SHIM(Comment),
-  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIContainerBoxObject, ContainerBoxObject),
   DEFINE_SHIM(CustomEvent),
 #ifdef MOZ_WEBRTC
   DEFINE_SHIM(DataChannel),
 #endif
   DEFINE_SHIM(DataTransfer),
   DEFINE_SHIM(DOMCursor),
   DEFINE_SHIM(DOMException),
   DEFINE_SHIM(DOMRequest),