diff -r 000000000000 -r 6474c204b198 dom/base/DOMCursor.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/base/DOMCursor.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,85 @@
+/* -*- 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 "DOMCursor.h"
+#include "mozilla/dom/DOMCursorBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(DOMCursor, DOMRequest,
+                                   mCallback)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(DOMCursor)
+  NS_INTERFACE_MAP_ENTRY(nsIDOMDOMCursor)
+NS_INTERFACE_MAP_END_INHERITING(DOMRequest)
+
+NS_IMPL_ADDREF_INHERITED(DOMCursor, DOMRequest)
+NS_IMPL_RELEASE_INHERITED(DOMCursor, DOMRequest)
+
+DOMCursor::DOMCursor(nsPIDOMWindow* aWindow, nsICursorContinueCallback* aCallback)
+  : DOMRequest(aWindow)
+  , mCallback(aCallback)
+  , mFinished(false)
+{
+}
+
+void
+DOMCursor::Reset()
+{
+  MOZ_ASSERT(!mFinished);
+
+  // Reset the request state so we can FireSuccess() again.
+  mResult = JSVAL_VOID;
+  mDone = false;
+}
+
+void
+DOMCursor::FireDone()
+{
+  Reset();
+  mFinished = true;
+  FireSuccess(JS::UndefinedHandleValue);
+}
+
+NS_IMETHODIMP
+DOMCursor::GetDone(bool *aDone)
+{
+  *aDone = Done();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DOMCursor::Continue()
+{
+  ErrorResult rv;
+  Continue(rv);
+  return rv.ErrorCode();
+}
+
+void
+DOMCursor::Continue(ErrorResult& aRv)
+{
+  MOZ_ASSERT(mCallback, "If you're creating your own cursor class with no callback, you should override Continue()");
+
+  // We need to have a result here because we must be in a 'success' state.
+  if (mResult == JSVAL_VOID) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  Reset();
+  mCallback->HandleContinue();
+}
+
+/* virtual */ JSObject*
+DOMCursor::WrapObject(JSContext* aCx)
+{
+  return DOMCursorBinding::Wrap(aCx, this);
+}
+
+} // namespace dom
+} // namespace mozilla