Bug 1323023 - remove nsAllocator.h; r=erahm

Nothing includes it, and it's not even exported from xpcom/base/.

xpcom/base/nsAllocator.h

@@ -1,17 +0,0 @@
-/* -*- 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/. */
-
-////////////////////////////////////////////////////////////////////////////////
-// obsolete
-////////////////////////////////////////////////////////////////////////////////
-
-#ifndef nsAllocator_h__
-#define nsAllocator_h__
-
-#include "nsAgg.h"
-#include "nsIFactory.h"
-
-#endif // nsAllocator_h__