function _updateListItemSelection(listItem, selectedFile) {
        var shouldBeSelected = (selectedFile && $(listItem).data(_FILE_KEY).fullPath === selectedFile.fullPath);
        ViewUtils.toggleClass($(listItem), "selected", shouldBeSelected);
    }
Updates the appearance of the list element based on the parameters provided.
@private
@param {!HTMLLIElement} listElement
@param {?File} selectedFile