Move m_pendingStateObject from Document and FrameLoader to DocumentLoader. It seems like we should only need one place to store the pending state object, and DocumentLoader seems like a good place to me. This is forked off from https://bugs.webkit.org/show_bug.cgi?id=33571 Brady says he "can imagine at least a few scenarios where it might not be safe or correct." Brady, can you mention those here?