new [[HasProperty]] invariant for non-extensible objects

Raul-Sebastian Mihăilă raul.mihaila at gmail.com
Mon Mar 6 10:10:32 UTC 2017


To be more explicit, the invariants allow this surprising behavior:

```js
Object.preventExtensions(nonStandardExoticObject);
Object.isExtensible(nonStandardExoticObject); // false

'foo' in nonStandardExoticObject; // false

Object.getOwnPropertyDescriptor(nonStandardExoticObject, 'foo'); // {value:
2, enumerable: true, configurable: true, writable: true}
```
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