This is just a heuristic, anyway, and some of the usage is downright broken.
There are two cases here:
1 - Deciding what to do for get{Own,}PropertyDescriptor. In these cases, we can
just enter with GET and rely on the filtering machinery to filter out dangerous
setters for security wrappers.
2 - Custom Xray props. None of these make sense in a |set| context. In fact,
they generally have null setters anyway, so we can just assume GET.
The policy-entering code in XrayWrapper is super haphazard. We'll get rid of it
entirely later in these patches.
This is just a heuristic, anyway, and some of the usage is downright broken.
There are two cases here:
1 - Deciding what to do for get{Own,}PropertyDescriptor. In these cases, we can
just enter with GET and rely on the filtering machinery to filter out dangerous
setters for security wrappers.
2 - Custom Xray props. None of these make sense in a |set| context. In fact,
they generally have null setters anyway, so we can just assume GET.
The policy-entering code in XrayWrapper is super haphazard. We'll get rid of it
entirely later in these patches.
The naming scheme for Xray typedefs is the concatenation of the tuple:
({SC,}, {Security,Permissive}, Xray, {XPCWN,DOM}). This is admittedly a bit
much, but I think it's still better than explicitly doing the "typdef Foo Xray"
everywhere. Moreover, once the new DOM bindings are done, the last component
in the tuple will go away.
Switch from using the interface objects from the Xrays compartment to wrapping
interface objects and interface prototype objects in Xrays. Make dom binding
Xrays deal with both instance objects and interface and interface prototype
objects.
We do this for delete_, enumerateNames, and resolveOwnProperty. This doesn't change
existing behavior, because for ProxyXrayTraits and DOMXrayTraits the expando object
will (currently) always be null.
For new DOM proxies, we could probably use the Xray expando machinery for the
regular expando object as well, and free up one of the reserved slots. That's
more than I want to bite off for the moment, though.
I also decided not to block on bug 760095 and just kick the problem of globals
with new binding down the road a little bit.
I'm not sure this stuff is correct for non-WN objects. Hopefully that will
come out in review.
Anyway, with this change, the expando infrastructure in XrayTraits is now
fully generic and non-WN-specific. To make things work for other objects,
we now need to implement the virtual traps and hoist the code that calls the
expando machinery out of XPCWrappedNativeXrayTraits.
