Firefox 65 keeps up the POWER

Firefox 65, thanks to the continued heroic efforts of the Talos and Power ISA community, finally builds out of the box on this Fedora 29 little-endian Talos II without any patches. The marquee feature in this release is WebP support (as demonstrated in Google's WebP gallery). As always, make sure your Rust and C compilers are up to date, and you will probably need to update cbindgen in cargo. Among other bugs swatted, this version of Firefox fixes issues with jemalloc on systems that use a 64K page size (most though not all Linux distros currently supporting ppc64(le), including Fedora 29 which I'm typing in), so ac_add_options --disable-jemalloc should no longer be necessary in your .mozconfig.

Firefox 66 is currently not buildable due to bug 1521713, but hopefully we'll have that on beta before it goes to release (it's a matter of fixing some flubbed release asserts).

Meanwhile, I've completed the Ion code generator, Baseline code generator, shared inline cache code generator, trampoline, lowering and move emitter for the Firefox POWER9 little-endian JIT. Still left to do are the macroassembler and the low-level assembler, though that is actually fairly straightforward, just tedious. It was very helpful to crib off my own work for TenFourFox's IonPower and some TenFourFox code will live on in the POWER9 port even after the last Power Mac G5 has blown its liquid cooler. I don't think I'll make it in time for the next ESR (which should be Firefox 67), but I'm reasonably confident I can get it in around Firefox 69 or 70 based on my current rate of progress.