The compartment-per-addon code was added so that we could segregate at least
some of the code from system-privileged add-ons into tagged compartments, even
when it ran in browser windows. That allowed us to apply certain special
behavior to them, such as enabling e10s shims, and to track some performance
characteristics.
The only remaining chrome-privileged add-ons now are system add-ons controlled
by us, and the shim system and per-compartment performance metrics are gone,
it no longer serves a purpose.
MozReview-Commit-ID: Ap186bWAaqP
--HG--
extra : rebase_source : c5bf81b44dd42b7cebce2784b7dd98480b41b593
83371fe0b5