code: function _createUnattachedMasterEditor(doc) {
          // attach to the hidden containers DOM node if necessary
          if (!_$hiddenEditorsContainer) {
              _$hiddenEditorsContainer = $("#hidden-editors");
          }
          // Create an editor
          var editor = _createEditorForDocument(doc, true, _$hiddenEditorsContainer);
          // and hide it
          editor.setVisible(false);
      }
docs: Creates a hidden, unattached master editor that is needed when a document is created for the
  sole purpose of creating an inline editor so operations that require a master editor can be performed
  Only called from Document._ensureMasterEditor()
  The editor view is placed in a hidden part of the DOM but can later be moved to a visible pane
  when the document is opened using pane.addView()
  @param {!Document} doc - document to create a hidden editor for