ES6+ to ES5 transpilation should disallow get name() and set name() properties

[patstuart]

Take the following example:

class Foo {
    get name() {
        return "bar";
    }
}

This transpiles to: (link)

var Foo=function(){};
$jscomp.global.Object.defineProperties(Foo , {
    name: {
        configurable: !0,
        enumerable: !0,
        get: function() {
            return "bar"
        }
    }
});

This is technically incorrect ES5, since the name property is not supposed to be configurable. According to this, this might break PhantomJs. We found this issue internally after a Safari 9 iPad threw the following error:
TypeError: Attempting to change configurable attribute of unconfigurable property. (I could not reproduce this error outside of our testing environment, so I'm guessing this is a browser quirk).

[MatrixFrog]

Hm, maybe we just misread the spec. If we transpile to configurable: false instead of configurable: true then would that be correct?

[patstuart]

@MatrixFrog Well I'm less of an expert than you, but I wouldn't think that would work, since the Function.name is already set and not configurable, and thus cannot be updated.

[MatrixFrog]

It looks like configurable: true is actually correct: Object.getOwnPropertyDescriptor({get name() { return 'name'; }}, 'name').configurable returns true. So I guess this is a bug in Safari, or in PhantomJS?