Last modified: 2014-11-11 01:20:11 UTC
In notifications.js an Icon is created which has no name. An additionalClass loading is what renders the icon. Introduced in patch https://gerrit.wikimedia.org/r/#/c/172425/ We should create mw-ui-icon-ajax (or icon-ajax for stable/beta) On a side note: Icon class should throw an error if no name parameter is given.
Prioritization and scheduling of this bug is tracked on Trello card https://trello.com/c/edxeE6B4