Stand by for FPR14 SPR1 chemspill

Mozilla has shipped a fix for MFSA2019-18 in Firefox 67.0.3 and 60.7.1. This exploit has been detected in the wild, and while my analysis indicates it would require a PowerPC-specific attack to be exploitable in official TenFourFox builds (the Intel versions may be directly exploited, however), it could probably cause drive-by crashes and we should therefore ship an urgent fix as well. The chemspill is currently undergoing confidence tests and I'm shooting to release builds before the weekend. For builders, the only change in FPR14 SPR1 is the patch for bug 1544386, which I will be pushing to the repo just as soon as I have confirmed the fix causes no regressions.

This chemspill also holds up the FPR15 beta which was actually scheduled for today. Unfortunately, the big JavaScript update I've been trying to make for the last couple cycles also ran aground and will not be in FPR15 either. There is a smaller one and some other improvements, so this is not an empty release, but I'll talk more about that in a few days.