TenFourFox 40 is a thing, but changesets only, available from SourceForge. It starts up, passes the JavaScript test suite, does browsery things and doesn't crash. Unfortunately 40 took longer than I had planned to get off the ground and I think we'll have to do a "38.9" to buy us one more cycle; in the meantime, I've decided to skip a step by jumping directly to 43 and cross my fingers that it works. If I find a serious regression, I'll have to decide whether I want to back up to 41 or 42. If not, the third milestone will be the first 45 beta.

Builders take note that MacPorts gcc 4.8 is now required; gcc 4.6 will no longer build the browser and even adding back the compatibility shim from 38 will probably not be sufficient (not only will it probably not compile, it won't link either due to required C++11 atomics support). However, I'd still like to get other compiler choices available since MacPorts is kind of a rickety platform base and always subject to some degree of breakage. If people try Sevan's pkgsrc gcc or Misty's Tigerbrew gcc, I'd like to hear your comments about how well they functioned and/or what was needed to get them working.

http://tenfourfox.blogspot.com/2016/03/progress-to-tenfourfox-45-milestone-1.html