All icons should have a tooltip if they are unlabeled
As per our UX guidelines, all icons should have a tooltip if they are unlabeled
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10220/diffs
The tooltip should be a bootstrap tooltip, rather than a browser tooltip. No icon should have a bootstrap AND browser tooltip.
If an icon does have both currently, they should be combined.
Ex:
If an icon has a browser tooltip only, it should be changed to a bootstrap one: