This isn't used anywhere. The only search results for \.timeStamp\b in Codesearch are:
- Uses of the DOM EventListeners's timeStamp property.
- Uses of ve.track's (not mw.track) timeStamp property.
Steps:
- Identify and migrate any uses of the timeStamp field, in mw.trackSubscribe callbacks.
- Remove timeStamp field to mw.track.
- Consider moving mw.now definition from startup module (critical path, short cache) to mediawiki.base (parallel, long cache).