Invalid ES6->ES5 lowering of static name & length methods

[ochafik]

Function.length and Function.name are not writable, which means the following valid ES6 code is not lowered properly:

class Foo {
  static name() {}
  static length() {}
}
console.log(typeof Foo.name); // function
console.log(typeof Foo.length); // function

Is currently lowered to:

var Foo=function(){};
Foo.name=function(){};
Foo.length=function(){};
console.log(typeof Foo.name); // string
console.log(typeof Foo.length); // number

And should be lowered to something like:

var Foo=function(){};
Object.defineProperty(Foo, 'name', {value: function(){}});
Object.defineProperty(Foo, 'length', {value: function(){}});
console.log(typeof Foo.name); // function
console.log(typeof Foo.length); // function

(this bug came up in some DDC-compiled Dart code)

[ChadKillingsworth]

That would work for ES5, but not ES3.

[ochafik]

(note: for DDC we're only after ES6->ES5 lowering)
Also, same issue with caller, callee, arguments, etc.

[ChadKillingsworth]

I think ES6 -> ES3 is probably a small minority (except by accident because that's the default).

I wonder if we can do an ES6 -> ES5 transpilation early, then do a very late ES5 -> ES3 transpilation at the end. That would allows us to convert things like Object.defineProperty after all the other checks and optimizations were complete.