QF19 summary

[classilla]

https://ehsanakhgari.org/blog/2017-08-11/quantum-flow-engineering-newsletter-19

M1386555 https://hg.mozilla.org/projects/date/rev/24fad9deb6a98e39a73b62cc4dd609bc1cda59fa (JS)
M1382837 (ion only) https://hg.mozilla.org/integration/mozilla-inbound/rev/5e8015a81320 (JS)
https://bugzilla.mozilla.org/show_bug.cgi?id=1383343 (JS)

M1385395 https://hg.mozilla.org/mozilla-central/rev/9529eb7b4087

[classilla]

Couldn't get the first part of 1383343 to work (multiple failures), and the second part depends on it.

[classilla]

Spun off M1382837 into #427 -- the Ion-only approach never actually executes, so we need a Baseline version for our prior-to-CacheIR build.