diff -r 000000000000 -r 6474c204b198 dom/bindings/Date.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/bindings/Date.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,59 @@
+/* -*- 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/. */
+
+#include "mozilla/dom/Date.h"
+
+#include "jsapi.h" // for JS_ObjectIsDate, JS_NewDateObjectMsec
+#include "jsfriendapi.h" // for js_DateGetMsecSinceEpoch
+#include "js/RootingAPI.h" // for Rooted, MutableHandle
+#include "js/Value.h" // for Value
+#include "jswrapper.h" // for CheckedUnwrap
+#include "mozilla/FloatingPoint.h" // for IsNaN, UnspecifiedNaN
+
+namespace mozilla {
+namespace dom {
+
+Date::Date()
+  : mMsecSinceEpoch(UnspecifiedNaN<double>())
+{
+}
+
+bool
+Date::IsUndefined() const
+{
+  return IsNaN(mMsecSinceEpoch);
+}
+
+bool
+Date::SetTimeStamp(JSContext* aCx, JSObject* aObject)
+{
+  JS::Rooted<JSObject*> obj(aCx, aObject);
+  MOZ_ASSERT(JS_ObjectIsDate(aCx, obj));
+
+  obj = js::CheckedUnwrap(obj);
+  // This really sucks: even if JS_ObjectIsDate, CheckedUnwrap can _still_ fail.
+  if (!obj) {
+    return false;
+  }
+
+  mMsecSinceEpoch = js_DateGetMsecSinceEpoch(obj);
+  return true;
+}
+
+bool
+Date::ToDateObject(JSContext* aCx, JS::MutableHandle<JS::Value> aRval) const
+{
+  JSObject* obj = JS_NewDateObjectMsec(aCx, mMsecSinceEpoch);
+  if (!obj) {
+    return false;
+  }
+
+  aRval.setObject(*obj);
+  return true;
+}
+
+} // namespace dom
+} // namespace mozilla