Security and patch rollup for FPR29 from ESR78

[classilla]

M1607762 https://hg.mozilla.org/releases/mozilla-esr78/rev/5aa243a2fe9d77578dd95ce3ab3a2aa6c1e92604
ceee64adc3b75dfac8828b9f48284b90de79dbe2

[classilla]

M1654620 https://hg.mozilla.org/releases/mozilla-esr78/rev/22335d5245ef
aba16c583e0c290ce18024295673f91bae4fbab8

Deferred:
https://hg.mozilla.org/releases/mozilla-esr78/rev/22b8bef3c436a4d36b586804f342928e1ab11e51
This looks like we may be affected but our code flow is different (especially in IonCaches.cpp), and I don't know the ramifications yet.

[classilla]

Not taking action on the patch above because I no longer believe it is reasonably exploitable on our platform.