Issue rendering metatags in Drupal 8 Beta 2

Upon updating to Drupal 8 Beta 2 and installing Formata, I came across another issue after enabling the theme:
Fatal error: Call to undefined function drupal_add_html_head() in /Users/karolus/Sites/drupal-8-beta/themes/formata/formata.theme on line 19

Disabling line 19 fixed it for the time. I did some research, but so far have not arrived at a solution. The theme appears to be working OK without this line of code, though.