Follow-up from "Resolve "Redesign activity feed""

The following discussion from !22217 (merged) should be addressed:

• @leipert started a discussion:

  @wortschi Hugh, it seems like we forgot to add the new class at: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/assets/javascripts/vue_shared/components/icon.vue#L3 Would you mind creating a follow-up to add it there?

The svg icon size 14px needs to be added to https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/assets/javascripts/vue_shared/components/icon.vue#L3