We have two GetGlobalForObjectCrossCompartment calls on Xray wrappers, but fortunately they are easy to fix.

Wrappers are per-compartment, not per-realm, so this will simplify the next patch. Also, considering the upcoming Realms proposal, it might eventually be possible to have multiple globals in a sandbox compartment.

Pushed by jandemooij@gmail.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/49dceb93cc0c part 1 - Remove unused CompartmentPrivate::isAddonCompartment. r=bholley https://hg.mozilla.org/integration/mozilla-inbound/rev/4cd7934210cc part 2 - Add a CompartmentPrivate::isSandboxCompartment flag and xpc::IsInSandboxCompartment(obj). r=bholley https://hg.mozilla.org/integration/mozilla-inbound/rev/450f74df066e part 3 - Rename GlobalHasExclusiveExpandos to CompartmentHasExclusiveExpandos and make it use IsInSandboxCompartment. r=bholley

https://hg.mozilla.org/mozilla-central/rev/49dceb93cc0c https://hg.mozilla.org/mozilla-central/rev/4cd7934210cc https://hg.mozilla.org/mozilla-central/rev/450f74df066e