Web Timing should be enabled for the Qt port.
This involves the following:
1. Implement http://trac.webkit.org/browser/trunk/WebCore/platform/network/ResourceLoadTiming.h
2. Flip WEB_TIMING flag
FYI, http://calendar.perfplanet.com/2011/a-practical-guide-to-the-navigation-timing-api/ mentions lack of Safari support as a drawback to the usefulness of the Navigation Timing API (despite support in the latest versions of IE, FF, and Chrome).
This probably should be a blocker for enabling Navigation TIming by default (bug 48923), as I'm not sure that exposing part fo the interface without the network times is a good idea.
Also, #c0 should have said Mac instead of Qt -- copy/paste error.
It is enabled for OS X 10.10.