diff -r 000000000000 -r 6474c204b198 dom/indexedDB/IDBWrapperCache.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/indexedDB/IDBWrapperCache.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,64 @@
+/* -*- 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/. */
+
+#include "IDBWrapperCache.h"
+#include "nsCycleCollector.h"
+
+USING_INDEXEDDB_NAMESPACE
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(IDBWrapperCache)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(IDBWrapperCache,
+                                                  DOMEventTargetHelper)
+  // Don't need NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS because
+  // DOMEventTargetHelper does it for us.
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(IDBWrapperCache,
+                                                DOMEventTargetHelper)
+  if (tmp->mScriptOwner) {
+    tmp->mScriptOwner = nullptr;
+    mozilla::DropJSObjects(tmp);
+  }
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(IDBWrapperCache,
+                                               DOMEventTargetHelper)
+  // Don't need NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER because
+  // DOMEventTargetHelper does it for us.
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mScriptOwner)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(IDBWrapperCache)
+NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
+
+NS_IMPL_ADDREF_INHERITED(IDBWrapperCache, DOMEventTargetHelper)
+NS_IMPL_RELEASE_INHERITED(IDBWrapperCache, DOMEventTargetHelper)
+
+IDBWrapperCache::~IDBWrapperCache()
+{
+  mScriptOwner = nullptr;
+  ReleaseWrapper(this);
+  mozilla::DropJSObjects(this);
+}
+
+void
+IDBWrapperCache::SetScriptOwner(JSObject* aScriptOwner)
+{
+  NS_ASSERTION(aScriptOwner, "This should never be null!");
+
+  mScriptOwner = aScriptOwner;
+  mozilla::HoldJSObjects(this);
+}
+
+#ifdef DEBUG
+void
+IDBWrapperCache::AssertIsRooted() const
+{
+  MOZ_ASSERT(cyclecollector::IsJSHolder(const_cast<IDBWrapperCache*>(this)),
+             "Why aren't we rooted?!");
+}
+#endif