diff -r 000000000000 -r 6474c204b198 dom/indexedDB/IDBWrapperCache.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/indexedDB/IDBWrapperCache.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=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/. */
+
+#ifndef mozilla_dom_indexeddb_idbwrappercache_h__
+#define mozilla_dom_indexeddb_idbwrappercache_h__
+
+#include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/dom/indexedDB/IndexedDatabase.h"
+
+BEGIN_INDEXEDDB_NAMESPACE
+
+class IDBWrapperCache : public DOMEventTargetHelper
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(
+                                                   IDBWrapperCache,
+                                                   DOMEventTargetHelper)
+
+  JSObject* GetScriptOwner() const
+  {
+    return mScriptOwner;
+  }
+  void SetScriptOwner(JSObject* aScriptOwner);
+
+  JSObject* GetParentObject()
+  {
+    if (mScriptOwner) {
+      return mScriptOwner;
+    }
+
+    // Do what nsEventTargetSH::PreCreate does.
+    nsCOMPtr<nsIScriptGlobalObject> parent;
+    DOMEventTargetHelper::GetParentObject(getter_AddRefs(parent));
+
+    return parent ? parent->GetGlobalJSObject() : nullptr;
+  }
+
+#ifdef DEBUG
+  void AssertIsRooted() const;
+#else
+  inline void AssertIsRooted() const
+  {
+  }
+#endif
+
+protected:
+  IDBWrapperCache(DOMEventTargetHelper* aOwner)
+    : DOMEventTargetHelper(aOwner), mScriptOwner(nullptr)
+  { }
+  IDBWrapperCache(nsPIDOMWindow* aOwner)
+    : DOMEventTargetHelper(aOwner), mScriptOwner(nullptr)
+  { }
+
+  virtual ~IDBWrapperCache();
+
+private:
+  JS::Heap<JSObject*> mScriptOwner;
+};
+
+END_INDEXEDDB_NAMESPACE
+
+#endif // mozilla_dom_indexeddb_idbwrappercache_h__