Translate "Loading..." text in inline comments
Summary: Ref T12616. This cements the relationship between ChangesetList (parent container) and Changeset (child) and passes translations down so Changeset can use them to translate the text "Loading..."
Test Plan: Viewed loading changes.
Reviewed By: chad
Maniphest Tasks: T12616
Differential Revision: https://secure.phabricator.com/D17846