Bug 1733075 part 4 - Add tests for some for-in edge cases. r=iain

function testNonEnumerableVisited() {

    // Non-enumerable properties must still be included in the duplicate-property

    // checking.

    var proto1 = Object.create(null);

    Object.defineProperty(proto1, "x", {enumerable: true, value: 1});

    var proto2 = Object.create(proto1);

    Object.defineProperty(proto2, "x", {enumerable: false, value: 1});

    for (var p in proto2) {

        throw "Shouldn't enumerate any properties";

    }

    var o = Object.create(proto2);

    for (var p in o) {

        throw "Shouldn't enumerate any properties";

    }

}

testNonEnumerableVisited();

function testEnumerableOnProto() {

    var iter = o => {

        var props = [];

        for (var p in o) { props.push(p); }

        return props;

    };

    // Test dense elements on the proto chain are included.

    var props = iter(Object.create({0: 1}));

    assertEq(JSON.stringify(props), '["0"]');

    // Test typed array elements on the proto chain are included.

    props = iter(Object.create(new Int32Array(2)));

    assertEq(JSON.stringify(props), '["0","1"]');

    // Test sparse elements on the proto chain are included.

    props = iter(Object.create({1234567: 1}));

    assertEq(JSON.stringify(props), '["1234567"]');

}

testEnumerableOnProto();