Fix Get/Set being enumerable

[pathurs]

Fixes #3610

[msftclas]

All CLA requirements met.

[pathurs]

Note: I just followed the normal convention of setting enumerable: false, however it may be better to not set enumerable at all, which should default to false on it's own. (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty)

@sheetalkamat Let me know what you think, seeing as you have already approved these changes.

[RyanCavanaugh]

@sandersn let's bundle this in with the rest of the class field changes when we document what's happening

@pathurs can you fix the merge conflicts please? Sorry for the delay in getting this in

[sandersn]

I missed this in 3.7 when I was adding ES-compliant class field emit. However, I think it's better to put it into 3.9 now than to wait any longer.

[pathurs]

@sandersn Thanks for merging from master, I don't know how I missed the notifications on this

[sandersn]

Travis fails because it still thinks that we're using submodules for the user tests. Not sure why.

[sandersn]

Thanks for your patience on this @pathurs

[ntucker]

Does this affect the types for keyof T when T has getters?

[DanielRosenwasser]

No, this affects emit, not the type system.

[benpetermorris]

This is a significant breaking change in our case. The UI library we use (Telerik's Kendo) uses property enumerability to convert "plain" objects to the Observable variant it uses within its UI classes.

With this change, property definitions are excluded from the conversion and the associated properties are no longer present on objects retrieved from Kendo's containers.

I support standards, of course, but it would be nice if there was an option to keep the old behavior. I'd be surprised if the new behavior is as innocuous as its low profile in the changelog seems to suggest.

[deltakosh]

I agree with @benpetermorris. This has a massive implication for library using TS

[iMarv]

We have been struggling with this breaking change aswell as we were relying on being able to enumerate over getters.
Our solution now is to use the following decorator on all getters that shall be included when enumerating the objects:

function Enumerable(
    target: unknown,
    propertyKey: string,
    descriptor: PropertyDescriptor
) {
    descriptor.enumerable = true;
};

class Testi {
    @Enumerable
    get prop(): string {
        return 'moin';
    }
}

I guess this is a bit hacky, but the cleanest solution we could come up with.