--- a/dom/bindings/DOMJSClass.h
+++ b/dom/bindings/DOMJSClass.h
@@ -6,61 +6,30 @@
 #ifndef mozilla_dom_DOMJSClass_h
 #define mozilla_dom_DOMJSClass_h
 
 #include "jsfriendapi.h"
 #include "mozilla/Assertions.h"
 
 #include "mozilla/dom/PrototypeList.h" // auto-generated
 
-class nsCycleCollectionParticipant;
-
-// We use slot 0 for holding the raw object.  This is safe for both
-// globals and non-globals.
-#define DOM_OBJECT_SLOT 0
+#include "mozilla/dom/JSSlots.h"
 
-// We use slot 1 for holding the expando object. This is not safe for globals
-// until bug 760095 is fixed, so that bug blocks converting Window to new
-// bindings.
-#define DOM_XRAY_EXPANDO_SLOT 1
-
-// We use slot 2 for holding either a JS::ObjectValue which points to the cached
-// SOW or JS::UndefinedValue if this class doesn't need SOWs. This is not safe
-// for globals until bug 760095 is fixed, so that bug blocks converting Window
-// to new bindings.
-#define DOM_OBJECT_SLOT_SOW 2
+class nsCycleCollectionParticipant;
 
 // All DOM globals must have a slot at DOM_PROTOTYPE_SLOT.
 #define DOM_PROTOTYPE_SLOT JSCLASS_GLOBAL_SLOT_COUNT
 
 // Keep this count up to date with any extra global slots added above.
 #define DOM_GLOBAL_SLOTS 1
 
 // We use these flag bits for the new bindings.
 #define JSCLASS_DOM_GLOBAL JSCLASS_USERBIT1
 #define JSCLASS_IS_DOMIFACEANDPROTOJSCLASS JSCLASS_USERBIT2
 
-// NOTE: This is baked into the Ion JIT as 0 in codegen for LGetDOMProperty and
-// LSetDOMProperty. Those constants need to be changed accordingly if this value
-// changes.
-#define DOM_PROTO_INSTANCE_CLASS_SLOT 0
-
-// Interface objects store a number of reserved slots equal to
-// DOM_INTERFACE_SLOTS_BASE + number of named constructors.
-#define DOM_INTERFACE_SLOTS_BASE (DOM_XRAY_EXPANDO_SLOT + 1)
-
-// Interface prototype objects store a number of reserved slots equal to
-// DOM_INTERFACE_PROTO_SLOTS_BASE or DOM_INTERFACE_PROTO_SLOTS_BASE + 1 if a
-// slot for the unforgeable holder is needed.
-#define DOM_INTERFACE_PROTO_SLOTS_BASE (DOM_XRAY_EXPANDO_SLOT + 1)
-
-static_assert(DOM_PROTO_INSTANCE_CLASS_SLOT != DOM_XRAY_EXPANDO_SLOT,
-              "Interface prototype object use both of these, so they must "
-              "not be the same slot.");
-
 namespace mozilla {
 namespace dom {
 
 typedef bool
 (* ResolveOwnProperty)(JSContext* cx, JS::Handle<JSObject*> wrapper,
                        JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
                        JS::MutableHandle<JSPropertyDescriptor> desc, unsigned flags);
 

--- a/dom/bindings/DOMJSProxyHandler.cpp
+++ b/dom/bindings/DOMJSProxyHandler.cpp
@@ -1,17 +1,17 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  * vim: set ts=2 sw=2 et tw=99 ft=cpp: */
 /* 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 "mozilla/Util.h"
 
-#include "DOMJSProxyHandler.h"
+#include "mozilla/dom/DOMJSProxyHandler.h"
 #include "xpcpublic.h"
 #include "xpcprivate.h"
 #include "XPCQuickStubs.h"
 #include "XPCWrapper.h"
 #include "WrapperFactory.h"
 #include "nsDOMClassInfo.h"
 #include "nsGlobalWindow.h"
 #include "nsWrapperCacheInlines.h"

--- a/dom/bindings/DOMJSProxyHandler.h
+++ b/dom/bindings/DOMJSProxyHandler.h
@@ -12,16 +12,18 @@
 #include "xpcpublic.h"
 #include "nsStringGlue.h"
 
 #define DOM_PROXY_OBJECT_SLOT js::PROXY_PRIVATE_SLOT
 
 namespace mozilla {
 namespace dom {
 
+class DOMClass;
+
 enum {
   JSPROXYSLOT_EXPANDO = 0,
   JSPROXYSLOT_XRAY_EXPANDO
 };
 
 template<typename T> struct Prefable;
 
 class BaseDOMProxyHandler : public js::BaseProxyHandler

new file mode 100644
--- /dev/null
+++ b/dom/bindings/JSSlots.h
@@ -0,0 +1,46 @@
+/* -*- 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/. */
+
+/**
+ * This file defines various reserved slot indices used by JavaScript
+ * reflections of DOM objects.
+ */
+#ifndef mozilla_dom_DOMSlots_h
+#define mozilla_dom_DOMSlots_h
+
+// We use slot 0 for holding the raw object.  This is safe for both
+// globals and non-globals.
+#define DOM_OBJECT_SLOT 0
+
+// We use slot 1 for holding the expando object. This is not safe for globals
+// until bug 760095 is fixed, so that bug blocks converting Window to new
+// bindings.
+#define DOM_XRAY_EXPANDO_SLOT 1
+
+// We use slot 2 for holding either a JS::ObjectValue which points to the cached
+// SOW or JS::UndefinedValue if this class doesn't need SOWs. This is not safe
+// for globals until bug 760095 is fixed, so that bug blocks converting Window
+// to new bindings.
+#define DOM_OBJECT_SLOT_SOW 2
+
+// NOTE: This is baked into the Ion JIT as 0 in codegen for LGetDOMProperty and
+// LSetDOMProperty. Those constants need to be changed accordingly if this value
+// changes.
+#define DOM_PROTO_INSTANCE_CLASS_SLOT 0
+
+// Interface objects store a number of reserved slots equal to
+// DOM_INTERFACE_SLOTS_BASE + number of named constructors.
+#define DOM_INTERFACE_SLOTS_BASE (DOM_XRAY_EXPANDO_SLOT + 1)
+
+// Interface prototype objects store a number of reserved slots equal to
+// DOM_INTERFACE_PROTO_SLOTS_BASE or DOM_INTERFACE_PROTO_SLOTS_BASE + 1 if a
+// slot for the unforgeable holder is needed.
+#define DOM_INTERFACE_PROTO_SLOTS_BASE (DOM_XRAY_EXPANDO_SLOT + 1)
+
+static_assert(DOM_PROTO_INSTANCE_CLASS_SLOT != DOM_XRAY_EXPANDO_SLOT,
+              "Interface prototype object use both of these, so they must "
+              "not be the same slot.");
+
+#endif /* mozilla_dom_DOMSlots_h */

--- a/dom/bindings/moz.build
+++ b/dom/bindings/moz.build
@@ -17,16 +17,17 @@ EXPORTS.mozilla.dom += [
     'CallbackFunction.h',
     'CallbackInterface.h',
     'CallbackObject.h',
     'DOMJSClass.h',
     'DOMJSProxyHandler.h',
     'Date.h',
     'Errors.msg',
     'GeneratedAtomList.h',
+    'JSSlots.h',
     'NonRefcountedDOMObject.h',
     'Nullable.h',
     'PrimitiveConversions.h',
     'TypedArray.h',
 ]
 
 FAIL_ON_WARNINGS = True
 

--- a/dom/workers/DOMBindingBase.cpp
+++ b/dom/workers/DOMBindingBase.cpp
@@ -1,17 +1,16 @@
 /* -*- Mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 40 -*- */
 /* 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 "DOMBindingBase.h"
 
 #include "jsfriendapi.h"
-#include "mozilla/dom/DOMJSClass.h"
 #include "nsContentUtils.h"
 #include "nsWrapperCacheInlines.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
 USING_WORKERS_NAMESPACE
 
 DOMBindingBase::DOMBindingBase(JSContext* aCx)

--- a/dom/workers/Worker.h
+++ b/dom/workers/Worker.h
@@ -3,18 +3,16 @@
  * 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_dom_workers_worker_h__
 #define mozilla_dom_workers_worker_h__
 
 #include "Workers.h"
 
-#include "mozilla/dom/DOMJSClass.h"
-
 BEGIN_WORKERS_NAMESPACE
 
 namespace worker {
 
 JSObject*
 InitClass(JSContext* aCx, JSObject* aGlobal, JSObject* aProto,
           bool aMainRuntime);
 

--- a/js/xpconnect/src/XPCJSID.cpp
+++ b/js/xpconnect/src/XPCJSID.cpp
@@ -2,17 +2,16 @@
 /* vim: set ts=8 sts=4 et sw=4 tw=99: */
 /* 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/. */
 
 /* An xpcom implementation of the JavaScript nsIID and nsCID objects. */
 
 #include "xpcprivate.h"
-#include "mozilla/dom/DOMJSClass.h"
 #include "mozilla/dom/BindingUtils.h"
 #include "mozilla/Attributes.h"
 #include "XPCWrapper.h"
 #include "JavaScriptParent.h"
 
 using namespace mozilla::dom;
 using namespace JS;
 

--- a/js/xpconnect/src/XPCJSRuntime.cpp
+++ b/js/xpconnect/src/XPCJSRuntime.cpp
@@ -31,17 +31,16 @@
 #include "nsCCUncollectableMarker.h"
 #include "nsCycleCollectionNoteRootCallback.h"
 #include "nsScriptLoader.h"
 #include "jsdbgapi.h"
 #include "jsfriendapi.h"
 #include "jsprf.h"
 #include "js/MemoryMetrics.h"
 #include "mozilla/dom/AtomList.h"
-#include "mozilla/dom/DOMJSClass.h"
 #include "mozilla/dom/BindingUtils.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/Attributes.h"
 #include "AccessCheck.h"
 #include "nsGlobalWindow.h"
 
 #include "GeckoProfiler.h"
 #include "nsJSPrincipals.h"

--- a/js/xpconnect/src/xpcpublic.h
+++ b/js/xpconnect/src/xpcpublic.h
@@ -13,17 +13,17 @@
 #include "js/GCAPI.h"
 
 #include "nsISupports.h"
 #include "nsIURI.h"
 #include "nsIPrincipal.h"
 #include "nsWrapperCache.h"
 #include "nsStringGlue.h"
 #include "nsTArray.h"
-#include "mozilla/dom/DOMJSClass.h"
+#include "mozilla/dom/JSSlots.h"
 #include "nsMathUtils.h"
 #include "nsStringBuffer.h"
 #include "nsIGlobalObject.h"
 #include "mozilla/dom/BindingDeclarations.h"
 
 class nsIPrincipal;
 class nsIXPConnectWrappedJS;
 class nsScriptNameSpaceManager;