Split out from bug 805052, item 12: RescueOrphans in XPCWrappedNative, which has a cross-compartment wrapper as parent??

OK, so RescueOrphans is meant to deal with an XPCWrappedNative whose parent gets reparented. For an XPCWrappedNative to have an interesting (non-global-object) parent, it needs to have a PreCreate hook. We have the following PreCreate hooks in our codebase: 1) nsDOMConstructorSH::PreCreate, which calls nsDOMConstructor::PreCreate, which does SetParentToWindow(win, parentObj), so the parent always ends up being a window. 2) nsEventTargetSH::PreCreate which does: *parentObj = native_parent ? native_parent->GetGlobalJSObject() : globalObj; where native_parent is an nsIScriptGlobalObject and globalObj is the aGlobalObj that was passed in. 3) nsDOMClassInfo::PreCreate, which does "*parentObj = globalObj;". 4) ComponentsSH::PreCreate, which does: *parentObj = self->GetScope()->GetGlobalJSObject(); 5) BackstagePass::PreCreate which sets *parentObj to global->GetGlobalJSObject(), where global is an nsIGlobalObject. That's it. So the parent always ends up being a global, and those of course never get reparented. Given that, we can just kill off RescueOrphans entirely.

https://hg.mozilla.org/integration/mozilla-inbound/rev/d71b934c28ee https://hg.mozilla.org/integration/mozilla-inbound/rev/be654bd9e20d https://hg.mozilla.org/integration/mozilla-inbound/rev/32176c758b4d

Backed out in for bustage: https://hg.mozilla.org/integration/mozilla-inbound/rev/945a30df1b0a https://hg.mozilla.org/integration/mozilla-inbound/rev/238076a16f5a https://hg.mozilla.org/integration/mozilla-inbound/rev/fa2a3978652a https://treeherder.mozilla.org/logviewer.html#?job_id=6597859&repo=mozilla-inbound

The problem was bug 1117242. Repushed: https://hg.mozilla.org/integration/mozilla-inbound/rev/7a3153f07028 https://hg.mozilla.org/integration/mozilla-inbound/rev/9a66f24829d9 https://hg.mozilla.org/integration/mozilla-inbound/rev/af5f70c0286a

https://hg.mozilla.org/mozilla-central/rev/7a3153f07028 https://hg.mozilla.org/mozilla-central/rev/9a66f24829d9 https://hg.mozilla.org/mozilla-central/rev/af5f70c0286a