function _createLiveDocumentForFrame(doc) {
        // create live document
        doc._ensureMasterEditor();
        _liveDocument = _createLiveDocument(doc, doc._masterEditor);
        _server.add(_liveDocument);
    }
@private
Creates the main live document for a given HTML document and notifies the server it exists.
TODO: we should really maintain the list of live documents, not the server.
@param {Document} doc