This was surprisingly tricky - due to the need to look up superclasses, class trait instantiation requires an active `Activation` and `UpdateContext`. We can't get those during VM instance creation, since the player needs the VM first before it can give it a context to work with. Ergo, we have to tear the global scope initialization in two. At the first possible moment, the player calls a new `load_player_globals` method that initializes all class traits in global scope.
I have no idea why this is necessary - I was in a context where what *should* have been a `NativeMethod<'gc>` was instead being interpreted as some different function type with all the same lifetimes, but with an extra `'gc` lifetime as well. Funneling this through a non-trait method bypasses whatever is going on with the trait solver, and then at that point the trait solver knows what to do. Consider this an extra level of conversion.
ECMA-262 3rd ed. doesn't mention anything about different number types, so the standard as-if rule applies. If we are going to distinguish number types, we have to treat them as if they were the same type, promoting to `f64` as necessary to facilitate the conversion. I took a cursory look at an ECMA-262 4th ed. draft and it appears to do the same, although it calls everything `GeneralNumber` and has some really confusing psuedo-Pascal syntax for some reason.
I am extremely glad AVM2 does not provide access to 64-bit integer types (for now, at least).
Namespaces as values adds a bunch of extra special cases to the coercion and equality rules that don't really belong there. Namespace itself just returns it's URI as a string, so we can just make `NamespaceObject` do that and then treat it the same way we treat boxed primitives.
These include:
* Name resolution in `newobject`
* All runtime & late-bound multinames
* `Object.hasOwnProperty`
* `Object.propertyIsEnumerable`
* `Object.setPropertyIsEnumerable`
So, I overlooked this reading the 1.45 documentation, but the first thing they did is completely change f64 conversions. Apparantly, what I was doing (and what JavaScript spec dictates) is actually considered UB in LLVM, and my ability to actually write a concise wrapping u32 conversion is actually a soundness hole in Rust. Ergo, I'm now emulating the wrapping and sign calculation, which makes this both passing it's tests again and free of soundness holes and UB.
I don't know why I'm doing this - tests are failing in CI but not locally, and I can only assume that the most obvious conversion is broken in some way on whatever other architecture GitHub Actions uses. This will explicitly mask the integer result as a u64, and then convert it down to u32. A not-broken compiler should treat this code identically.
AVM2 is based on ES4, which as far as I'm aware, does not distinguish between "primitive values" and "objects". Thus, it is expedient to interpret any statement requiring something to be an Object to mean "not null or undefined".
Since we internally represent register values with primitive types, it is important that the VM always coerces to object before doing any other sort of type checking. Hence, something like `as_object` is unhelpful as it accidentally enforces a primitive/object distinction that ES4 attempted to remove.
Note that this does NOT completely test the full range of if instructions for abstract relational comparison. Notably, the Adobe Animate CC compiler compiles each operator into it's negated equivalent, e.g. `<` becomes `ifnlt`.
I do not know how to get it to emit `ifge` or the like, which differ only by how they handle `NaN`s.
David Wendt