Latest master. Editing a page that was created a minute earlier.
Placie the following in MediaWiki:Common.js:
mw.trackSubscribe( '', function ( topic, data ) { console.log( '[mw.track] ' + topic, data ); } );
Output:
[mw.track] event.Edit [mw.track] timing.ve.performance.system.domLoad.mwTarget 2149.39599609375 [mw.track] timing.ve.performance.system.activation.mwTarget 5442.916015625 [mw.track] event.Edit [mw.track] timing.ve.behavior.firstTransaction.undefined 2311.072998046875
I don't think that's supposed to contain "undefined".