function installUsingDialog(urlOrFileToInstall, _isUpdate) {
        var isLocalFile = (urlOrFileToInstall instanceof File),
            dlg = new InstallExtensionDialog(new InstallerFacade(isLocalFile), _isUpdate);

        return dlg.show(urlOrFileToInstall.fullPath || urlOrFileToInstall);
    }
@private
Show the installation dialog and automatically begin installing the given URL.
@param {(string|File)=} urlOrFileToInstall If specified, immediately starts installing the given file as if the user had
    specified it.
@return {$.Promise} A promise object that will be resolved when the selected extension
    has finished installing, or rejected if the dialog is cancelled.