Make Function.(name|length) configurable

[Yury Selivanov]

This is an important feature for OOP libraries: typically classes are emulated using functions, hence class *static* properties are properties of the function object that represents the class.  Since '.name' and '.length' properties are read-only and non-configurable for functions, there is no way to have '.name' and '.length' static properties for classes.

This is something that has already been fixed in Chrome and Firefox:

- https://bugzilla.mozilla.org/show_bug.cgi?id=1084019
- https://chromium.googlesource.com/v8/v8/+/f6cd009efd7a032907b11265e74102b0d45207a1%5E!/

And InternetExplorer doesn't have any restrictions on these properties, which leaves WebKit/Safari the only browser that doesn't support this.

[Yury Selivanov]

In short, the following should work:

function f(){};
Object.defineProperty(f, 'name', {value: 'g'});

[Simon Pieters (:zcorpan)]

*** Bug 158062 has been marked as a duplicate of this bug. ***

[Simon Pieters (:zcorpan)]

Test for "length" in test262 at

https://github.com/tc39/test262/blob/83b27c9beb7b3ea78b319148b5c82a5411a333b1/test/language/statements/function/13.2-15-1.js#L19

[Mark Lam]

This is already fixed in ToT.  You can verify this for yourself using Safari Technology Preview or a WebKit Nightly build (https://webkit.org/downloads/).